While not the best of what the series has to offer, Metroid II makes with what it has, and that's fine enough for the GB
The game begins panned in fron of your ship (the first time you SEE Samus's ship in the Metroid series), and go right from there, blasting everything you see. Samus sprite is detailed and large, and looks nice on the GBA SP's recoloring of the game. The backgrounds are fair, but not very memorable, but the tight controls make up for the graphics, as most Metroid games tend to do. For a series remembered for it's amazing backdrops, it's dissapointing, but you must remember you are looking at 15 year plus old hardware, so it didn't have much to work with.
The music and sounds are not what you'd expect from Metroid either. The tune you hear in the main menu will grate your ears till' they bleed, and the main area's tune is a bit peppy for Metroid, but it's a very memorable tune, it'll stick in your head, but you wo't be humming it though.
The story picks up pretty much after Samus' last NES adventure, this time on SR388, due to Metroid activity or somesuch other reason. You go on and kill a plethora of Metroid in a more arcade style than the other games, meaning, you start pretty much empty handed, and you kick every last Metroid's ass to get power-ups. It's more linear than the Prime series and the other two original adventures, but it works.
The fun you get from this game depends on how sypathetic you can be to old Game Boy games. If you've gone out and sold your GB Family to get the shiny new DS and PSP, then forget this game, it's bleepy bloopy soundtrack, mixed with it's detailed, but bland sprites will probably bore you to death. But, if you have a head for the old-school, pick this game up, take the road less traveled, and you'll probably find some things you didn't know from Metroid. As for me, I'll pray for a remake.