This is a personal favorite of mine, and I'm actually convinced it's Disney's most underrated animated movie. I guess the main reason I like this film so much is that it features the most sincere depiction of a relationship between siblings in any Disney film. For once, we get real, flawed (and therefore all the more lovable) people - not the usual perfect Disney princesses. But it's also incredibly funny and spectacularly entertaining throughout (not to mention that it has one of the most hilarious intros in any sci-fi film ever). I simply adore this movie, and I'm not ashamed to admit it makes me cry every time I watch it. This and Sanders' and DeBlois' other masterpiece, the first HOW TO TRAIN YOUR DRAGON, are the cinematic medicine that get me through my darkest days.
The look of the film is very distinct and refreshingly different from Disney's previous animated features. And the visuals are gorgeous; the backgrounds are painted in beautifully faded watercolors, and the 2-D animation is an example of artists at the peak of their craft. Every scene is jock-full of original ideas and a virtual demonstration of Chris Sanders' and Dean DeBlois' seemingly limitless imagination (the film also features a ton of clever references to sci-fi and monster films). Simply one of the best animated films - and one of the funniest sci-fi comedies - of the last 20 years.
P.S. (for new IMDb users): In case you don't know whether to trust this review or not, because you have no idea what my tastes in film are, just click on my username - gogoschka-1 - and you'll see a list what my 50 favorite movies are.