SpiderMan on BROADWAY? It's the freaking apocalypse. Holy idea-with-bad-written-all-over, Batman!
Sarcasm aside, I think it could be good. I will definitely wait until I hear some music before I make any actual judgments. I doubt it will be the next Phantom of the Opera/Wicked/insert name of popular musical here, but it could be really cool if it's pulled off right.
That, and I would really love to see the Green Goblin flying around on a glider onstage. My inner nerd cries in happiness at the thought.
Bow before the cuteness of my cousin!!! ;]