I'm a new owner of this device. I noticed lots of the reviews are old so I wanted to leave notes to other tinkerers.

I often set up my devices more than actually play them. This has been a problem with me with this device so far.

• Great D-pad and buttons.
• Screen is nice and big and bright.
• It's nice and lightweight compared to my RG351MP.

• Included screen protector is only okay. It seems to be a hair too big for it so its bubbling on the corners for me even though it looks like its perfectly placed. You only get one try at it before you have to ship another one out from China or something.
• Limited CFW support.

• Really really good latency.
• Not many features, but games play very well.
• I really want to sync save states to other devices with SyncThing, so this OS is lacking in this department.
• You can use Skrapy to add all the metadata and media to your library, but it takes some settings adjusting on Skrapy that weren't super obvious on my first attempt.

• I installed GammaOS first thing because the stock Android seemed very boring and bare bones.
• I expected to get better sleep battery life but it's about the same. I'm looking for full device hibernation and this doesn't seem to have it.
• Extremely high input lag out of the box with SNES. I had to tweak many settings to cut it down a bunch, but it doesn't compare at all to the stock Linux OS even with read ahead. Other systems like Genesis seem the same.

• A/B buttons are backwards unlike the stock OS.
• The dedicated hotkey button no longer does anything, but I actually prefer the original Select key hotkey combos.
• My major disappontment (so far) is that the OS has some sort of save state manager that automatically messes with the RetroArch config when you load it. So even if you override it to a location that's shared, it resets and then no longer syncs. This is okay if you want to cloud sync just for this one device, but if you want a universal system between many devices it's doesn't appear to be compatible.
• If I wanted to switch between stock OS and Rocknix, the TF2 slot expects roms to be in /roms for Rocknix and / for stock, so the games library doesn't work between OS's. I think this is more of Anbernic's fault as I think most OS's use a /roms folder.

More comments to come as I learn more.