This was almost perfectly constructed. Throughout the movie, I found my eyes scanning every inch of the screen, trying to catch a clue as to where the next scare is going to come from. It takes a little while to get to the real scares, but the back story makes the scares come from a real place. Definitely recommended if you're looking for an unconventional horror movie that relies more on a genuine sense of fear rather than a collection of "gotcha" moments.
I could not recommend "Up" more. It's such a beautiful, funny, sad, thrilling, imaginative, emotional journey. The animation is gorgeous, the ideas are consistently inventive, the voice-over work is inspired, its sadness is perfectly balanced with its light humor and it's one of the most fulfilling emotional rides I've had in a movie theater. Go see it! Now! Right now!