I went to see it with my mother. My experience seems to mirror yours I think. For her part, my mother was rather nonplussed by the musical number and the old man with bird poop on the side of his head trying to save a porcupine. She's kind of a casual fantasy fan; she digs movies and TV shows about magic, witches and wizards and attractive guys being noble and she'll watch anything with Merlin in it, but she wouldn't sit down to read novels, much less ones on the scale of Tolkien's work. When the movie was over she told me she was disappointed in the lack of female characters (which I could in some small way agree with, though I was glad to see so many awesome beards in one flick), and she thought the story would be more about Gollum and the ring. Overall she seemed to like it, or so she told me, anyway.
It's kind of interesting how the superficially silly elements of the movie are aimed squarely at the hardcore fans who know what to expect, while in another property that sort of thing would be thrown into an otherwise serious story in a probably misguided attempt to appeal to a broader demographic.