If you have a 17" laptop, then you know your choices for bags are small. I've always had good luck with Targus accessories, and this backpack is no exception. It's well constructed and made of good materials.
The compartments are varied and evenly distributed and (mostly) easy to access. The backpack is very adjustable, from the shoulder straps, to the waist strap, to the pouch straps (which allow you to place bulkier items in the inner pouch). The outer pouch/compartments even flip open with snap-clips for easier access).
There is no "one size fits all" for laptop bags, but this bag seems to have room to spare. I have a Toshiba P105-S9722 17" widescreen laptop that weighs in near 10lbs with the power supply included. The laptop slides effortlessly into the padded compartment (which is at the "bottom" meaning closest to your back when worn as designed). The compartment has a velcro strap to help prevent sliding. The compartment above the laptop has a sturdy base as yet another level of protection to prevent potential damage of your laptop. I find this very useful because I place my powersupply (1lb+ brick), power cord, and other misc. cords in there.
I've used this backpack as carry-on while traveling from NH to CA, and it was packed solid, but everything was very accessible and it still managed to fit under the seat as per airline regulations and JUST met the height/width/depth maximum limits. This may vary from airline to airline though. I had my Toshiba + power supply & cord, iPod, PSP (+ games), a few DVD's, two changes of clothes, a cordless USB mouse in the outer sidepocket, cordless shaver in the inner section, cell phone in the shoulder-strap mounted pouch (which is removable via clip and can be attached to your waist, or anywhere you wish), plus usb cables and various adapters, headphones, etc in various compartments, a couple magazines, a book, and some basic toiletries. It was not lightweight, but properly adjusting the straps helps, and wearing the waist strap for extended use is key!! I walked from one end of O'Hare to the other and although the weight had me winded (as any luggage would), the straps never hurt my shoulders, nor did I feel any discomfort from the laptop being against my back!
I would also like to add that the design of the compartments make it fairly simple to access wha tyou need without a lot of rummaging (provided you don't stuff too much into each one).
For the price, this is an exceptional backpack for those with big laptops that need to carry a lot of accessories, or travel.
Why not 5 stars? For the size, a bit of "modularity" would have been great. When you're not traveling or "packed to the gills" it would be nice to be able to "zip off" or unclip about half of the backpack. This could have been done with the same clips that the outer portion adjusts and opens up with. I would also like to have seen a specifically padded compartment for the laptop power supply, or at least a velcro solution for immobilizing supply & cord. These however, are minor issues, and this backpack is fantastic.