Aside from some... questionable boss fights, and some maddening side missions involving Wisps, Generations was SUPERB. Play it at 60 fps on PC with all setting cranked up. My mind melted.
The tiered movement system being introduced in Lost World more or less addresses the one control issue with Generations, which was how finicky and imprecise it could be negotiating tricky platforms when your character's tendency is to blast forward at the slightest touch.
Also, put me in the camp that really digs the Lost World art style. It's not as "textured" as Generations, but as others have mentioned, the crisp clear design makes all of the elements POP off the screen. And really, I just love the repetition of patterns -- the spirals and checkers and slanted planks of wood all add up to create something you want to -run- on and -jump- off. An inviting platform paradise, if you would.
Really eager to hear some hands-on impressions now.