Well, playing Corruption at the moment and loving every minute of it so far. I'm only about 7 hours into it, but what I've played has been great.
The controls were easy to get used to and prove to be much more accurate and intuitive than the control schemes of the previous Metroid Prime installments. The motion controls are alsoquite enjoyable andsatisfying.
It seems to be much more epic than the previous Prime games, owing to the much more "open" nature of the level design. Not that the rooms are much larger in this game - it's just that there's less closed in rooms and corridors, and more open-air areas with alien vistas. That's another good thing about this game - the art direction is brilliant - particularly impressive is the first time you land on Bryyo. Other than that, it seems to play much like Prime and Echoes - and that's not a bad thing!
My only negative is that sometimes the loading can get a little irksome. Sometimes when you shoot a door, you can wait outside for a full ten seconds before it opens. This is especially annoying when you're trying to get from one place to another quickly...
So yeah, brilliant game. I have to juggle between playing this and studying for my exams that are coming up at the end of the month. Usually I get my study out of the way, then play Corruption as a sort of reward. It seems to be working so far - I've been getting a few solid hours of study in every day!