I saw this last night. I went in with an open mind but wasn't expecting much - really haven't liked the other cartoon adaptions (xmen, superman, spiderman etc etc).
I was blown away.
A few people have mentioned bad acting, and cringe-worthy lines, however, I found this not to be the case (unlike the other movies mentioned earlier). It was by no means oscar stuff, but for me there were no cringe worthy lines. There were places where I was thinking 'Ah here comes the soppy', but to my surprise they refrained. The comedy was delivered almost flawlessly.
The effects - wow. You know, there are a lot of CG movies now and it was hard to think effects could get better but jeez this was a different level. I can't help but wonder whether or not this will translate to the small screen well enough - from what I saw this HAS to be watched at the cinema.