Yahtzee HAS to criticize games; he said so in the Orange Box review. I think he may like the game a LOT more than he's letting on, really. If he says that he'd love a game just about the space levels from Super Mario Sunshine, and then he gets a game that's just that, he can't be TOO hateful about it.
Anyway, I too have a few problems with Galaxy, even if I love it with all my heart and being. I want to press the "c" button to orient the camera to directly behind Mario, right-side up, similar to pressing "z" in any of the 3D Zelda games. However, the areas in which you can do this always seem extraordinarily limited, and you end up having to run TOWARDS the camera at times, something which is particularly nerve-racking. Even if it does let you use the "c" button, it seems to like orienting the camera upside-down. That, and the complaint about being unable to tell where a given push of the thumbstick is going to go is totally true.
One complaint I personally have is that the gravity doesn't work well. It's REALLY hard to tell at times whether letting go of whatever you're flying on will drop you to a planet, or if the game decides you're out of reach and drops your ass into space and death. Then there are those planets that are shaped really weird. If there's a part on a planet that's shaped like a U or a C, I try to long-jump from one tip to another to save time. If the planet just has a curve to it, I try to long-jump a few times along the inside of the curve to get there faster. However, all too often, neither of these techniques actually work. For the tip-to-tip jumping, the game seems to REALLY like keeping me bound to whatever surface I jumped off of. Unless I get within about 6 inches of the surface I'm trying to get to, it drops me back to the first tip where I then have to walk around to get to the point I could have spit on earlier. For the long-jumping on the inside of a curve, I don't know why the game tries to make my movement so wonky. Whenever I come down from a long-jump I made to cut to another part of the curve, the game always makes me move back some before I hit the ground. It's rather annoying.
Long-jumping seems to have been fucked over in general, really. On any of the smaller, round planetoids, running is faster than long-jumping, because as you long jump, you move in a relatively straight line as the world curves away, meaning the actual distance across the world you moved is pretty short. Then you have the extra time it takes for you to fall. While this technically makes sense, it hurts gameplay, to me. Plus, why have proper physics there where it makes it annoying, then have bullshit physics elsewhere when proper physics there would have been more helpful?
However, other than those complaints, the game is mind-blowingly fun. I think the life system is charming, even if it's useless.