It has been stated that dating in real life doesn't necessarily bring chemistry on screen. Personally, I think they have very good chemistry, although it was more evident in the first film.
Kell, I totally agree about Michael Sheen, but from what I see in film sites, Launter's choices for future roles appear to show that he's more interested in becoming a film star than a serious actor, unlike his co-stars.
As for Water For Elephants, I think it may be a quite solid films, because I've seen it in 4 film sites, unlike other rumours, like the one that he's going to be the new Spidey (which I highly doubt). I haven't read the book, but judging from the summary and the comment on this forum, it seems like a really good read.