I adored UP. It is one of my all time favorite movies... It is sad, at parts, and funny at times and those together make it "real" to me... Did you finish watching it? I know you're not the only one who thought it was too sad.
Yeah, it is sad at first. Then it gets good again. Ellie is still very much a part of Carl through all the adventures that come in this story. And a kid who needs a guy in his life gets Carl. Don't forget to look at the album shots at the end of the movie. It makes so much sense.
I'm planning to go back and finish it, for sure! It's sad, but in a really lovely way.