The opening credits music was pretty well done and in sync with the screen.....but it's not really a theme.
I'm not sure if they will keep Desplat as the composer on any future sequels. He's kind of a B+ grade composer, but this movie has proved the franchise worthy of an A lister's attention.
And even if they do keep him, I do hope they redo the music. It just wasn't very memorable for me.