I've been testing out a lot of different GBA games on the new emulator, I've noticed more than a few problems.
Glitches: A lot of text and graphics glitching in games. Some examples. In Yoshi's Island, the half the map screen is glitched mess as is the score board. In GT Advance 3 the cars tend to flicker awfully. Metroid Fusion after you get to the first statue it is supposed to show you the map and move a cursor from your location to the room you're supposed to go, normally it take 2 seconds for the move, here it takes more than a minute and you can't skip it, the music still runs at full speed. The Minish Caps menu transitions are painfully slow, music again at normal speed. Teenage Mutant Ninja Turtles when the level starts the screen has black horizontal line flickering over the entire screen. In Mortal Kombat Deadly Alliance enter a match and... well it's hard to explain, there are no fighters and the camera is flung all about the area with many graphical glitches on screen. Many other games have minor glitched text or flashes of white or color during screen transitions.
Freezing: This happens to a few games. Donkey Kong Country 3 and Steel Empire freeze on launch. Donkey Kong Country 2 the opening titles role as normal but it freezes right before the main menu. The Minish Cap, the controls freeze up after entering in my name. Iridion 3D freezes after the opening credits, it's sequel Iridion 2 freezes on launch, unlike the others freezes for the Iridion games I can't access the emulator menu and need to reset. Teenage Mutant Ninja Turtles glitches when the level starts as stated above but the controls are also frozen, eventually the screen goes black.
Slowdown: Most games are very playable with frameskip set at auto 2 or 3 but at certain times things slow. Often it's just small stutters but in Crash Bandicoots Huge Adventure, the water level turns the game into a powerpoint presentation no mater how the frame skip is set.
Aspect Ratio: The emulator has 3 settings for this, Normal, Medium and Full. Normal gives a smallish picture in the middle of the screen, 3:2 in native res. Full the picture is in 4:3 stretched and takes up the full screen. Medium is I assume supposed to be 3:2 aspect ratio at max size like the original REVO but it is just another 4:3 stretched.
More than half the games I tested seemed to work fine however haven't done many extended play sessions with them because I would not want to commit to a game knowing that at any point it could crash or catastrophically glitch. Unlike most of the other new emulators I would call the GBA one in it's current state unplayable in a practical sense for this reason. Starting a game with the intent to complete it is quite the gamble.
Unrelated to the GBA Emulator I ran into a problem with the menu. When attempting switching back to the old menu I accidentally clicked Mount USB, when after I pressed Enable Old DMenu it froze to a black screen, I could not even turn off the system. I had to find a screw driver and remove battery, it booted as normal after that thank goodness.