So I just got a chance to pick this game up.
Heres a short review
+Great production value
+Songs are a good mix of...hybrid music genres. If you're into that kind of stuff.
+Mechanics are like Beatmania, with the analog nub as record spin move. The formula is still fun.
Some things special: Fever, basically pressing x to increase a score multiplier...kind of like star power in GH, it speeds you up tho.
You can adjust the speed of the notes on the fly
+lots of different extras...like an ost mode (basically a soundtrack mode), mv mode(music video), challenges, free play, items (notes, skins and chars) that increase different things.
+Songs are a good length...2 min. Good for portable use.
cons:
some of the music can get a little wacky. the engrish is ok at some parts, gets really bad in other songs. if you get really bothered by that sort of shit.
its a good game, its nothing groundbreaking, but its a great experience on the psp.