Spiderman had fantastic sets and costumes, but I never got emotionally invested in the characters, and the music was so completely forgettable that I'm not sure I can hum a single tune from the show. Admittedly, I'm not that into the whole superhero/comics thing and largely went because CodeMonkey wanted to see it. I still felt that, had the show been well done, I would have enjoyed it. Visually, it was spectacular, but since it fails to either take the viewer on an emotional journey or at least provide some catchy song and dance numbers, it just falls completely flat. The music was completely un-moving and often downright painful to listen to.
Mary Poppins also lacks for character development or a really meaty plot (but then, I think the original Disney movie isn't abundant with either), but the music was charming and the sets were delightful. The viewing experience was more of a delightfully trippy romp through Edwardian London than a journey, but it was fun. Spiderman was less fun and more an aural assault.
That said, the folks at Disney did cut a scene I thought was rather important from Mary Poppins. From Wikipedia
Mr. Banks grows increasingly irate with his children's stories of their adventures, but Mary effortlessly inverts his attempted dismissal of her services into a plan to take his children with him to the Dawes Tomes Mousley Grubbs Fidelity Fiduciary Bank, where he is employed. On the way there, as they pass the bank, the children see "The Bird Woman" (Jane Darwell), of whom Mary sang to them the night before, and they want to feed the birds around her, but George will have none of it as he expresses his lack of interest in what Mary Poppins says and orders his children to "come along" and not mention her name for the rest of the day. Upon arriving at the bank, Mr. Dawes Jr (Arthur Malet) and Mr. Dawes Sr (Dick Van Dyke)—Mr. Banks' employers—aggressively try to persuade Michael to invest his tuppence in the bank to the point of actually snatching it out of his hand without waiting for his permission. When Michael protests, the other customers misunderstand and start a run on the bank that forces the bank to suspend business.
This was eliminated in favor of Michael and Jane snubbing The Bird Woman, requiring Mary Poppins to teach everyone a Very Important Lesson (beautifully sung, naturally). The run on the bank was eliminated completely in favor of another storyline which left Mr. Banks jobless. I was disappointed, and I'm not sure why the developed did this. Did they think modern viewers would't understand the idea of a bank run? Who knows.
In any event, it was a lovely day, though seeing two Broadway shows in one day is a bit much.