Brandon Davis of ComicBook.com was kind enough to write out what he saw in some detail:
I like the added/altered dialogue. I knew it wasn't going to be word-for-word but I was curious how much of the dialogue they'd change. It's a subtle enough difference that might not matter much to general audiences if wholly new scenes aren't included, but as someone who can recite the whole movie word-for-word, it's a bit of a relief. (That was actually my biggest source of annoyance in watching the stage version; outside of the new scenes, it's almost line-for-line exactly the same as the movie.)
According to various things I'm reading, it's of course visually impressive, and the talking animals (Zazu included) work really well to the point where it's so subtle that it looks like real footage even while they're speaking. Still no word on how the in-world musical numbers are going to shape up.