Wow, everyones opinion here is the complete ugly opposite to what the people over at GameFaqs think( they literally worship the game there xD ).
I personally happen to like this game, and reversals aren't that hard. I can pull them off pretty much all the time. Theres some crucial timing to reversals, thats all.
Also, i find there is some depth to the moves you can pull off, and the game doesn't seem like coaching to me. Sorry, but I just can't see the huge flaws that all of you see in this game. Overall, its a better improvement over the old PS2 game of Rumble Roses. Tho I'll admit that not having a storyline for each of the girls, sucks.. but it doesn't bother me that much.
As for unlocking costumes, you have to pay attention to each of the girl's hints stated in the "SHOP" section of the game under "EDIT COSTUMES" where you can buy new costumes normally. Each question mark has a hint. Some of them are pretty obvious too as to what you need to do(check out gamefaqs for answers to the hints, theres a big topic on it over there on the RRXX board).
At any rate, think what ya all will.. Some people think it sucks, some like it. To each their own opinion I guess. But this game certainly isn't the worst game to come out on Xbox 360 yet. I can think of other games which I think suck, but I won't bring that up here XD