Saw it today and really enjoyed it, although, as Dacey said, the trailer did spoil some things.

In many ways darker and more complex than the first, plus the flying scenes were in my opinion much better here (plus there were more of them) Well-paced and beautifully animated,
especially Hiccup's expressions--truly breathtaking. Despite the trailer showing too much there were some things I totally didn't expect, which made the movie all that much better.
However, as good as this movie was, I prefer the first--it just had a more primal pull that I can't quite explain, and even with the more conventional plot there were some scenes that just took my breath away. This movie had some of that, but not as much as the first. But altogether definitely worth seeing. A hit for DreamWorks!

*
*They really need it too. At the beginning of the Penguin trailer I actually heard someone groan: "Oh
no." Not too many laughs for Home either.
You can’t just have your characters announce how they feel! That makes me feel angry!