I think the flying effect looks good as a whole, meaning with the lighting, the song, the guards rushing in, etc. I think it just works. Do I think it's the most spectacular thing they could come up with? Absolutely not, especially with a film studio backing the show, they could have come up with something a little more creative. This effect is in essence, the same they used for CATS twenty years ago for the tire levitating.
Certainly something could have been done to fly Elphaba sitting on the broom, which would have made more sense. So my conclusion is that the effect is OK and is a good end of first act, but certainly not the best they could have done.
The meat is always leaner on somebody else's dinner plate!