Love it! Perfect for me on many levels. I am able to fit SO much in it! It works great for international travel too. I put a neck pillow (in an Eagle Creek small compression bag), a change of clothes ( in small compression bag) into the bottom of the middle compartment. Then, on top of those two bags I put another small lightweight backpack with my Nikon camera inside of that pack. I put a toiletries, ear buds, pens, pencils, notepad, and orher easily acessable items in the front section. I use the back section for my laptop and kindle. It could still fit a lot more. I use as my carry on. It fits under most seats IF not packed to the max. Great pack!
I bought this bag for school and traveling with my laptop, knowing that this would not be my edc bag. I love Osprey bags, I think their shoulder straps/suspension and back panel on this pack are spot on with what I expected from them.
Getting through TSA with my laptop was super quick. I ended up zipping through in front of 2 people that were fighting to get their laptops out of their bags as I just unzipped mine - so that was pretty awesome.
As for fitting under the seat - I did not have this bag packed full so I was able to stuff it under the seat. If it was stuffed full it would have been another 2-3 inches or so deeper and would not have fit under the seat (Spirit under-seat limits are: 18" x 14" x 8") The bag is at least 19" x 12" x 10", although I did not measure to confirm. I used 2 medium ebags packing cubes fully packed and had my 15.6" HP laptop in the back, there was room for a lot more in the bag, but I wanted it to fit under the seat (see photo attached).
My complaints with the Osprey bag is a complaint I have with a lot of bags/packs -- the side compression straps go around a water bottle. When you take the water bottle out, the bag is not compressed, this is just annoying as it makes the bottle harder to get out if you have the straps pulled tight.
Other than that, the organization and compartments in this bag are great and provide a space for everything I need for class.