I agree, I like that movie a lot, too. Michael Keaton was still his wiseass persona, but his character showed a certain amount of subtlety, and you started off kinda hating him, or at least thinking he was a real dick, but by the end you come around. Which is of course one of the main points of the film.
I like Henry Winkler in it, too. Henry was still working on the whole "I am not Fonzie" thing, and I think this film helped him a lot, too.
Shelly Long, well, I don't know if I ever liked her that much, but I did find that one scene (you know the one) surprisingly pleasant. That's about all I can say about her. Her character was a bitch and honestly didn't change a lot over the course of the film, but maybe she wasn't supposed to. It was all about Keaton and Winkler, and they both nailed it.