I cannot say enough good things about this bag. I have started to travel more often lately and I needed a backpack that would fit all my clothes for 4 day quick trips but with economy ticket seating (economy seating on some airlines you are only allowed one bag) so I needed to be able to fit all my items into this bag. I pair this bag with amazon's airtight bags&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/8-Travel-Space-Saver-Storage-Bags-for-Clothes-No-Vacuum-or-Pump-Needed-Reusable-Packing-Sacks/dp/B01GEP4JGA/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">8 Travel Space Saver Storage Bags for Clothes - No Vacuum or Pump Needed - Reusable Packing Sacks</a>. This helps me get all my clothing in, with extra shoes, a good book, and toiletries. The other pockets are roomy and can fit most things I need quickly. I don't travel with a laptop so I can't comment on how a laptop would fit.
I fly mostly united/southwest/delta; I am able to fit this bag under all seats so far. It got a little tight on the aisle seat a couple times but I made it fit. Just keep that top pocket flat and you will be fine.
As a female with a small frame and only 5'0" this bag does look huge on me. But I don't care.

Only things I wish it could have: a keychain to hold my keys. I don't like keeping them in the front pocket, I am worried they will fall out. I like to secure them more. Rubber bottom so it sits up when on the ground. A removable shoulder strap would be nice too. I love how the straps go inside the bag. Very easy to move them.