Why are you surprised? Just not a fan of most animated films? And yea it is fantastic, especially those of us in our mid 20's and older, so much nostalgia.
Trailers didnt sell it well and Sarah Silverman annoys the hell out of me. I also felt marketing was lacking and as much as I love animated films, I dont see most of them in the theater. I mean I saw WiR when it came out but I was just reiterating how good it is because it currently on. It was definitely much better than expected.