I'm definitely intrigued but skeptical. I think any new version has to be completely different than the version with Mia Farrow and Robert Redford, and this one will definitely be different. However, knowing that the creators are the same ones who created the new version of Romeo and Juliet has me a little worried. I thought that one was WAY out there. And I agree with you about the music in the trailer. Hopefully that won't be a huge part of the film.
Judging from what little we can see in the trailer, I do think the movie will stay true to the themes and the debauchery of the "Roaring Twenties." I saw a brief flash of the eyes of Dr. TJ Eckleburg, so that tells me they will focus on the same kinds of symbols Fitzgerald focused on.
I like the characters for the most part. I hope Carry Mulligan can be detached and aloof as Daisy, and I have no doubts about Leo's abilities to capture Gatsby. I'm not sure about Toby McGuire as Carraway, but I think that's just because Toby McGuire bothers me for no apparent reason.
All in all, I'm excited about it, and I think it will be a good way to get my students excited about reading the book!