The audio in FF7 (not tried anything else yet) is a bit off.
Sound effects and midi instruments seem to be cut short.
I did a quick search but I didn't find anything.
There's a couple of other things I think might be worth thinking about:
-There should be a means to set a default directory for the rom browser, starting at the root directory when my roms are /sdcard/external_sd/psx/roms/ is a pain to navigate to at startup
-You should be able to enable navigation to directories with a period prefixing them ("hidden" folders in linux)
-The memory card selection should allow the selection of both mcd and mcr files since they seem to be compatible
-one of the things I miss from psx4droid is that if you quit it would make a save state and then load it again when the rom is next launched
-This is probably a big one but support of PSP EBOOT roms would be awesome
All in all good work! It runs a lot faster than PSX4droid