Summary observations:

Form Factor & Build
-The Tom Bihn ID bag fills a niche directly between the Super Ego and the Imago in terms of size, functionality and feature set. The soon to be released Ego will offer customers yet another messenger style bag in the volume range of the ID Bag but with a Super Ego heritage. Once the Ego is released, Tom Bihn aficionados will not be wanting for anything more in terms of messenger bag options.
- Geometrically, the ID looks and behaves like a hybrid between the curvaceous Super Ego and the rectilinear Empire Builder. It really reminds me of the classic saddlebags of a bygone era so often repeated in modern briefcase design. As such it's as aesthetically easy on the eye as it is a pleasure to hold.
- Any space into which the Super Ego can't fit, the ID Bag fits in easily. As I write this report, the ID Bag is directly beneath my airline seat. It could fit even more comfortably under my feet and below the seat ahead.

Ergonomics
-While the Super Ego is the maximum capacity one would want a messenger bag to be, the Imago is probably the minimum. The ID Bag hits the sweet spot in the middle. Fully loaded is was as cozy as any carry-on or personal bag would want to be. The renowned suspension shoulder strap absorbs pressure that would otherwise be transferred to the user's shoulders, making long hikes or hurried dashes less strenuous than with plain unpadded straps.
-Most important for users on the move- the waist strap keeps the ID Bag snug up to your waist- preventing jostling, sway and other potentially nasty luggage behavior.
- For the numerous occasions when a shoulder strap is not the right method for carry or manipulation, the outer hand strap makes the ID easy to maneuver. In general, luggage is much easier and faster to acquire in a rush by a quick grab of the handle, than by the shoulder strap.
- For right handed , left shoulder dominant users, the outermost flap pocket is a breeze to use for the quick retrieval and replacement of travel or other small documents or wallets. This reviewer happens to be one of those users and I can happily report that I find flap pockets indispensable
- The twin lined side pockets follow along the lines of those on the Imago, but they're larger- allowing for larger or bulkier payloads. In addition, they come supplied with zipper pull-cords for fast and fussless access. In addition, their zippers are designed with a deliberate gap or stand-off measuring about 1/2cm. This allows for snag-free egress of headphone or earbud cables. If you've ever chopped your earbud cables with the zipper, you'll appreciate this feature all the more.
- The structural balance of the ID bag rivals the svelte and nimble Imago with much less pitch than you would likely experience carrying the Super Ego.

Affordances
- Strategic pockets are where you'd want them to be. Obviously that's a subjective observation- or is it? High Gloss gadgets are all the rage- but scratches are so declassé! Thus...my highly scratch prone Samsung T809 phone as well as highly scratch-prone Black iPod Video - both found very plush and cozy homes in the respective Imago end pockets- all within easy reach.
-Releasing the adjustable main flap buckle and lifting the flap reveals three internal compartments- two are YKK zippered compartments and the third an open space that contains what most people would characterize as mobile warrior office tools.
- As is typical of Tom Bihn laptop specialized bags, the several pen and PDA sized slots fill up the back of this space, leaving the bulk of the compartment available for user specified contents. Also typical is the tethered lanyard with terminal clip for the attachment of keys. I just discovered a great use for these short lanyards. I now clip my iogear WiFi finder to the end, allowing for a quick sniff of my surroundings. In the past I've also found these tethers ideal for the attachment of pocket flashlights or other indispensable tools.
- The outer hand carry straps are a Godsend for the many moments when tossing the ID Bag into the back seat of a car or yanking it out of an overhead compartment is a chore by any other means.
- At times, the top flap will be open and you'll want a hand strap to maneuver the bag for one reason or another. At this moment the lighter duty inner hand strap is there just when and where you'll need it.
- With so many of us being active and as we become attached to favorite beverage brands, having your personal drink along for the ride is a nicety as well as a realistic way to ensure that a beverage is always at hand. The ID Bag has one beverage pouch that cinches to form fit to any bottle 10cm or smaller in diameter.

Other Notable Observations
The ID Bag's exterior panels are fabricated from Ballistic Cloth. Too reemphasize what we've stated before- this is premium luggage material that is well worth the cost. Not only is it much easier to keep clean than traditional Cordura fabric, but it's also noticeably softer to the touch. The ballistic weave, combined with Tom Bihn geometry results in luggage that maintains it's shape even when empty. This subtle advantage is hard to quantify but when you experience it, it becomes hard to turn back to standard weave Cordura nylon.
- The ID I chose has Black and Steel panels on the outside and Crimson inside. The combination is understated to the rest of the world and startling once the ID Bag is opened up.

Target Market- Anyone in need of a medium size messenger style bag that can carry up to a 17" MacBook Pro within an Archetype sleeve plus additional electronics, literature, personal belongings and a host of small accessories. It's ideal for daily school stuff as well as for transporting a decent collection of professional office tools. The ID Bag is perfect for customers that can't ever fill a Super Ego but that find the Imago to be just a tad space restrictive and the rule that the Empire Builder isn't as geared for shoulder carry.

Human Factors & Usability - Almost all the ordinary demands of a person carrying a laptop and the typical mix of gadgets in an urban environment are served elegantly by the ID Bag. It's typical of Tom Bihn designs in that it lacks superfluity, and yet all compartments and features are greedily filled and seem ideal given our urban toolsets. Our favorites are the outside handle strap and outside flap pocket as well as bottle holder. All hardware such as zippers and buckles are ergonomically placed for easy one-handed use. Outer and inner compartments support a logical distribution of contents. We found it easy to contain a basic laptop in a sleeve, AC Power supply, two extra batteries, a PDA, cell phone, iPod 30GB, reading glasses case as well as house keys and sundry writing implements.
It naturally carries well on the shoulder and is extremely well balanced (especially for biking) when supported by the belt strap. If you've been looking for a bag that's a hybrid between the traditional laptop carrier and a messenger bag, the ID Bag is sure to satisfy that need. The location of compartments supports intuitive accessibility , allowing for easy removal of stuff with little or no cognitive effort.

Styling and Aesthetics - The Imago earns high marks for styling and aesthetics. Taking a number of geometric cues from the much larger Super Ego and blending them with Empire Builder features, it strikes a balanced and elegant pose for student, executive or general user. As with most Tom Bihn laptop bags, the ID is gender, age and occupation agnostic.As with it's cousin the Imago, the ID abandons the boxy looking aesthetic typical of laptop carriers, for a more streamlined curvilinear silhouette instead. Its Unisex sensibility transcends age, occupation or cultural clique. Depending on the choice of color, it can be dressed up or dressed down. The color choices cover the basics of neutrals with primary accents:
Steel/Wasabi , Steel/Crimson , Steel/Steel , Sage/Deep Blue, Crimson/Steel, Kiwi/Steel , Grape/Wasabi  & Hunter/Steel 

Environmental Stress- The ID Bag, as with other Tom Bihn luggage, is designed to endure the trials and tribulations of campus or commute and it does so admirably. As a veteran user of the Super Ego, I felt right at home hauling the ID by hand or over my shoulder. With less protrusion and surface area than larger bags, the ID minimizes banging into people or inanimate obstructions. We performed our 10 minute shower test and can report that the ID is fully drench proof. Fully loaded and aggressively yanked about on it's maiden transatlantic voyage, it handled the typical demands of airline travel with aplomb.

Ease of Use- The ID Bag is extremely accommodating to the needs of its users. I found it to be very practical as a carry-on bag, easily substituting for the champion of carry-on's, the Aeronaut. No. You can't haul a laptop and three days worth of clothes in an ID Bag, but it performs well for the minimum of carry-on tasks. Best of all is that it goes directly from the airport to the boardroom without missing a beat. Due to it's clever compartmentalization, all one's essentials may be neatly organizedand quickly retrieved. Niceties such as zipper pull-cords and lined MP3/Phone pockets mustn't be underestimated. Carry comfort is easily overlooked by others, but in Tom Bihn's ID Bag, shoulder carry is secure and very well cushioned. Those shoulder straps are the Thermarests® of the shoulder strap world.Put the pad on your shoulder and you can be assured that it will not slip off! The exterior hand carry strap is cushioned at its core, allowing a hand to squeeze tight around the handle - with the extra 'give' absorbing the force of a swinging hand motion well.
Not once did a zipper snag or offer the slightest resistance to a quick and smooth opening. The ubiquitous main buckle operates as well as one might expect for this design. In truth, some may want a quick release 'seat buckle' option for speed of use. One minor annoyance that I encountered was that off the shoulder, the 'Fastex' type buckle's female member was sometimes tricky to 'pick up' as it hangs down lower than the bag's bottom - making a quick and elegant closure a feat of dexterity.

Task performance optimization- The Tom Bihn ID Bag earns top marks for hybridizing the Super Ego, Imago and Empire Builder so well. It's plenty big enough to be a small emergency go bag for escaping an office disaster but it it truly shines as a medium sized all around laptop carrier that can contain a wide variety of office, school or professional tools well.

Items of Note:
Excellent Customer Relationship Management |Superb design and construction quality| Logically arranged compartments and sub-compartments |Stands upright on a flat surface|Form fitting flexibility | Premium materials and hardware | Ideal for medium volume loads & active lifestyles |Exceptional comfort especially on bikes/mopeds/scooters | Understated or flamboyant color choices | An ideal hybrid between a messenger bag and a saddle bag style briefcase.