Edit: Erasing what I wrote re: the script to avoid giving the forum trouble.
In short: People who love the work of Fred Dekker and Shane Black will love this movie. Predator diehards who need the films to be very serious and masculine at all times will hate it. Like Iron Man 3, it's going to be a very polarizing experience for geeks. I loved the script but it is a huge departure and takes major liberties - but frankly that is what this franchise (and Alien, though that won't be getting it) needs.