I thought the movie was a brilliant display of film-making from one of the few directors who seems to be able to handle complex stories alongside a beautiful mix of practical and CG effects.
My only gripe (hence the 4 stars) is the final shot of the film which seems like Mr. Nolan is giving us a little nudge nudge, wink wink and making even the most oblivious of movie goers question what they just watched. The idea exclaimed so loudly by this final shot is planted throughout the film well enough already and simply causes problems by breaking the logical rules the film creates for itself throughout.