Oh man. So many. I don't want it to just be bagging on System76 and PopOS! though. I really bought in because I believed in the partnership, but I really believe that PopOS! has kinda 'lost track' of what they were trying to do.
System76 issues:
Battery life is basically a joke. I can't use the machine without it being plugged in.
For the price, the trackpad/ keypad/ keyboard experience is not great. I've had dells with better trackpads. At the price point I paid ($2200 in 2020), they are not a premium experience.
There have been no firmware updates to address issues like bluetooth or battery life.
Considering its built hand in glove with PopOS, depending on what update you are on, various things just break every-time, like audio or the popshop, or bluetooth.
That all being said, I'm an abusive owner, and its been a workhorse. I just can't recommend it based on its price-point. Everything just needs to be 'better', but mostly the hardware/firmware/OS relationship.
I still want an 'it just works' linux machine. The System76/PopOS! combo isn't there yet.