Every single plot of any story, movie, book, or television, has been 'done before.' It's simply a matter of making it in an innovative way. The 'underdog vs. giant empire of evil' has been done over since the beginning of written language, and yet star wars seemed to pull it off. I'd suggest not just writing off a movie just because of it's genre, bingo.

Anyway, yeah, it does look pretty cool. I wouldn't be nearly excited if it was anyone other than JJ Abrams. I was a huge Alias fan, I can't wait to see how he does this.