The main thing to keep in mind when purchasing Guitar Hero for the DS is, yes, it is for a DS. Nothings gonna change that. Even though the attachment can be awkward, I think the guys that made this game did about as good of job as can be expected. I mean, its not like your playing on a PS3 with a 52" flat screen. Of course its gonna be a little different. As long as you think realistically about what to expect before buying this game, you shouldn't be let down. You can still get into that cool little groove you get when your hitting all the right notes, so the rhythm is still there. The battles are okay. Again it took some ingenuity to make this game even playable at all so I give them points again for that... using the Mic to blow out the fire on your guitar was a pretty cool idea.
So yeah thats it. You can still have fun playing the game. Just don't expect TOO much from it... I mean, seriously, it's a DS.