just bought it this morning and already finished it(takes few hours first time through) and I gotta say this -
WOW
this game is stunning, graphics, music, atmosphere - this is Ico/Shadow of Colossus of XBLA Games!
for the uninitiated link to 1up review:
http://www.1up.com/do/reviewPage?cId=3169204
and screenshots:
http://www.1up.com/do/media?cId=3165777&sec=IMAGES
if you're low on funds(costs $15), at least download the demo, you'll see what I'm talking about ^^
absolutely beautiful score.
post your impressions if you tried it.

It's one of the most infuriating games I've ever played. About halfway through the fourth world, my brain exploded and I don't think I've been able to recover all the pieces yet...

hehe, at first they seem to be really hard.
they're very satisfying once you're done with them.
and funny thing is, I initially thought you couldn't get all the jiggies first time through,
but everything you see is obtainable at any given time, you just have to find proper technique.

Demo is great.  I intend on eventually buying the full version when I play through some more of the backlog I already have.