A number of years ago now, a friend researched and bought one of their earlier models (A P2, which is no longer sold). I liked his, so bought one for me, and another for my wife. We still have and use those, a good 10 years or so later.

I'm on occasion a long-distance backpacker, and at least on western trails you see a lot of ULA packs. I had switched to a lighter weight (Gossamer Gear) brand pack for doing long distance trips, but found I got about 2500 miles or so out of such a pack before it was getting pretty worn. My hiking partner on the Appalachian trail had been using a ULA Catalyst and replaced his at a store in Virginia, telling me at the time that he had over 5000 miles on the pack and that it was still useable. I ended up buying a ULA Circuit about halfway along on the AT, and the folks at ULA were great to work with, easy to replace my pack by mail mid-trip with them.

Okay, sorry to be so verbose, to cut to the chase --- I find ULA packs to be a pretty good compromise between somewhat conflicting priorities: weight, durability, comfort/features, and price. You can buy a lighter pack, but you might find at times that you need to load it beyond suggested design limits (with food and/or water if nothing else), and that it literally wears out faster, and/or that you just have to be a little more careful with it. You can buy a more "full featured" pack, but such will likely be heavier, and I find that ULA packs have --- for me --- just the right set of features that I really want.

I think I might have 3500 miles or so of backpacking on my Circuit now since I got it in 2010, and it's going strong. I could do another thru-hike with it with no concern about it holding up.

All that said, at least a couple of more mainstream "you can see it in a store" backpack manufacturers have come out with credible alternatives that didn't exist when I bought my first (and maybe even my more recent) ULA. Osprey has a good model or two I believe (where "good" is based on my own very subjective preferences), and I think there might be others now.