I saw the film a week ago and rather enjoyed it. Contrary to WierdRaptor's view, I liked that they killed off the father as the result was Hiccup maturing a little and taking up responsibility as a chief, plus it shocked me even though I sort of saw it coming.
I thought Hiccup's mother was a decent character, they could have forced her into the story and not have her appearance make any sense, yet the filmmakers were smart enough not to do that.
Agreeing with F-14 Ace, the villian was kind of a generic brute(kind of the same complaints I had about Tai Lung in the first KFP) and he certainly lacks the psychological depth of fellow Dreamworks villain Lord Shen.
But he was a decent antagonist all around, so he doesn't hurt the film that much. I liked the cinematography and the animation is what you would except from Dreamworks.
I think John Powell's soundtrack is what caught my attention the most, it is simply breathtaking, and to top it off is the piece 'Where No One Goes' that included vocals by Jonsi.
So all in all, this is probably the second best Dreamworks animated film I've seen(the first being Kung Fu Panda II) and I can't wait to see more from them.