The only problem I had with the demo is the damn camera freaking out. And a few screen tearing going on. Leon's campaign will be the best (if your an actual RE fan who cares about the survival horror thing). Some people bitched about it being too slow paced for them, but I thought it was perfect. I mean it was the beginning of the game after all, so of course you start out slow. Some things I noticed is that you can access weapons and items faster, change your aiming preference from either cross-hairs (for weaklings) or the classic red dot. You can even change the color of the dot from either red, blue, purple, yellow, or green.
Chris's campaign, though fun, will be my least favorite for obvious reasons. His segment of the demo was just far too easy.
Jake's was the most fun seeing as how I can go "Wesker" on enemies by using only hand-to-hand combat. His campaign is close to Chris since its all about action, but at least his feels like something new. In the boss fight against Ustanak (that big motherf*cker from the trailers) theres quite a few options you have on beating it. I would lay down charges, lure him to them, and detonate. Really looking forward to playing as him some more.
There is also a rumor that the game might have a fourth campaign where you play as Ada. If thats true, then my guess is that it won't be unlocked until after the other three are completed.
I'm excited for the game but Capcom needs to fix the bugs.
