I've seen video of the Screw Attack in action. The camera pulls out into a 3rd person perspective. Same with the wall jump. The deal with the Screw Attack is that it's a lateral-only maneuver. You can't gain altitude with it like you could in Super Metroid.

I actually haven't played Metroid Fusion. I'm actually planning on grabbing it when I head to Idaho next week to grab MP2 and Mario Power Tennis. I'm hoping that Dark Samus turns out to be as unbelievably badass as he/she looks.

From what I hear, the Light World/Dark World thing is really well done. The Dark World in particular is apparently nasty. IGN will be posting their full review later today, so I'm itching to see what they say about it.