I thought Fallon was better on the Tonight Show than his Late Night show, at least so far as one episode can show you. The beer pong with celebs crap doesn't really fly with me though, nor really do any of the other regular bits I've seen. Definitely more watchable than Leno, which wasn't even a given considering how little I thought of Jimmy Fallon in the few episodes of Late Night that I've caught. I don't think he is ever going to displace Conan for my late night loyalties or anything but I might be able to upgrade my opinion of Fallon from negative to at least neutral.
I think his choice of guests for his first episode was a little weak. Will Smith? U2? That would be a pretty hot show if half of it took place in 1987 and the other in 1997.
I'm really interested to see how Seth Meyers does. Fred Armisen is his band leader and drummer?
Really two of the better talents from more recent SNL. I think that has a chance to be really good.