The main thing I like is the hardware support. I knew before purchasing that everything would work, and that helped me feel okay dropping a pretty penny on a new laptop. Besides that, I'd say they're fine. They aren't designing and manufacturing their own hardware (at least not back when I bought one); the laptops are pretty standard off-the-shelf stuff. System76 just promises that it'll all work out-of-the-box. I've never used Pop!_OS, so I can't speak to that. Arch and Debian work great, though.

The only negative I can think of is: once the battery started to go after several years, they didn't have a replacement in their store, but because it's a generic laptop, there were new ones available on Amazon. It just would've been nice to get it from System76.

All-in-all, I'm a happy customer. I'm keeping my eye on Framework, though. The MNT Reform is also interesting. I don't like how thick it is, but that's because it uses 18650s for the battery, which would solve the problem of buying a new battery just to find that all the batteries were manufactured at the same time, so there are no working replacements.