I own two of his previous games and bought this the second it entered into the open-beta stage(I.e. people who pre-ordered got free access to the beta version of the game), it's a truly great game, and very fun.
I might also add, that when the final release version of the game comes, it will be priced higher than it currently is, kinda like Mount and Blade was, where the development version of the game(which included free update to the final) was comparatively cheap to the final retail version.