The 5200 was essentially an Atari 400/800 computer with 16KB of RAM, the older CTIA graphics chip (as opposed to the later GTIA), and analog joysticks rather than digital 8-way. A lot of games written for one platform have been ported to the other.
This emu is configured to act as an 800 with 64 KB. This probably makes the most sense for maximum compatibility. If you have a fave 5200 game, you will likely find an 800 version floating around on the interwebs that will run.
I tried several games out yesterday: Pacman, Pole Position, Blue Max, Frogger, Tempest Xtreem demo, Donkey Kong, and a few others. They all ran well with the exception of Berzerk, which would not load at all. It may have been a corrupted file, so I will try again.
The emulation is very good: graphics and joystick input are fine. The sound is a bit warbly and high-pitched, but that was with the A320's external speakers; maybe headphones would sound better.
This is an excellent addition to the Dingoo's library of emulators! _And_ it runs in native mode!