i was at an apple store and had one on display....the iphone attached had a wide range of music....being a heavy metal guy, i wanted to make sure it was good loud...it was very good....also sounded very good for classical, rap, dance, etc.
im think of buying it myself
the only negativity i heard was that when you turn it up really loud, the quality of sound degraded a bit....but i guess, from what i hear, you have to turn the volume WAY up, almost to the point to where its too loud anyways