First, let me point out that I only use this backpack for travel and not for every day carry. What I bring along when I'm traveling is different then what I carry when I go to work, but I see no reason why the Travel Pack wouldn't be an effective every day carry backpack. When not expanded it still offer plenty of storage space and is compact enough that it wouldn't look out-of-place. It's only that some features on the backpack such as the TSA friendly laptop compartment are less useful for everyday use.
I like the organization of the front compartment for smaller things that stays with the backpack and I want quick access to. I especially like the 4 pockets on the interior. They are along the sides of the backpack which leaves the main cavity of the backpack completely free. If you are a packing cube type of user then this is a great feature.
The ability to open the backup up like a suitcase allows quick and easy access to all my stuff which I appreciate a lot when I'm at a hotel. It gives me quick access to everything and not have to dig through layers to get to bottom items. I've also found this to also be useful at the airport and on the plane. I can get to items without messing up the way things were packed.
The Travel Pack is designed to keep its shape and stands up on its own, both of which I really like. The one downside of this when traveling on an airplane is that it might not fit in the space below the seats especially aisle seats. On a couple of trips, I've had to put it in the overhead compartment.
I'm not a 1-bag traveler (I generally have a carry-on with me) so I've not had to over pack the Travel Pack. I generally keep what I need access to when mobile in the backpack while keeping clothes and other items in my carry-on. The way I've packed is to utilize the backpack's organization pockets and pouches what I need when I'm mobile (e.g. at the airport) and use the Peak Design Tech Pouch for things that I need when I'm on the airplane. When I board the plane, I would put the backpack in the overhead compartment (if it doesn't fit underneath the seat) and keep the tech pouch with me which I hook to the back of the seat with a HeroClip. This helps me to have to keep going to the overhead during flight or try to wrestle with the backpack in the type airplane space.
Currently the total weight of the backpack when loaded with my typical travel accessories comes out to about 8.5 lbs (including the 3 lbs tech pouch and 1 lb headphones). My laptop and charger adds another 3 lbs so if this was all I need to bring then we're looking at under 12 lbs.
I've still not found a good way to use the quick access pocket at the top of the Travel Pack. It's too small to hold modern phones so other then using it to quick store some paper items like cash or get access to the charging cable (couldn't charge a phone when the zipper closed since the pocket is too small), I've not found much use of it. The hidden pocket along the back is also very tight that I've found it inconvenient to use. The water bottle hold does hold bottles tightly but it takes two hands to put a bottle in. I wish it was zippered so that I can use it for holding other things. Also when it is holding a water bottle it does pushes against the interior side-wall pockets.
The outside of the Travel Pack is kept looking clean and minimal so there's not o-rings or d-rings to attach stuff to the outside.
After multiple domestic and international trips with the Nomatic Travel Pack, I've found myself really liking it even more then I expected. It's been comfortable to wear and very convenient traveling with it through airports and on airplanes.