Oh good lord this is butchered. It's laggy to the brink of sluggishness with a 19 FPS framerate, the soundfont is totally different from the GBA original and not for the better, this is a total bastardization of what's otherwise a superb GBA classic.
Very great port of the 2001 original. Even with a bit of slowdown here and there, its still very, very playable. I actually got really used to it, and its the first version of the game I've played. I even completed this version 100% once, and it doesnt matter at all if the language of the game is only Japanese, the game is playable regardless of language, doesnt affect gameplay at all. In fact, it's mainly there to give you hints on the game. Another great extra bonus is the expanded playfield, or just widescreen, as it's normally called. Gives you more space in boss arenas and other things. Overall, a great port of the game, and the music in this version sounds great, it is ported from the GBA version with some entirely new tracks here and there (some songs from SONIC THE HEDGEHOG 4!) in original MIDI format, and it sounds great with the Android's MIDI soundfont. (It's a shame the team who ported this went uncredited, as this reconstruction of the game most likely took a lot of work.)