I wasn't too impressed on listening to the advanced bits and pieces, but now that I've heard it all in context I'm really enjoying the score. It's light hearted and fun - and doesn't take itself too seriously. It has a VERY British sensibility which a lot of Americans just don't seem to 'get', so I don't think it would particularly fare well on Broadway.
I don't think Zippel has ever since reached the dazzling heights of his City of Angels lyrics, but I thought this Cinderella lyric was rather Porter-esque (with all it's internal 'I' rhymes, and rhyming "her eyes on" with horizon"):
"Look at me, Cinderella, flying high in the skies
With her eyes on the horizon"