On the surface, Jack the Giant Slayer would appear to be made from the same cloth as Oz the Great and Powerful -- that is to say, it's an expensive CGI spectacle directed by a highly regarded helmer of superhero flicks (in this case, X-Men's Bryan Singer). It's based, of course, on the classic fairy tale in which a peasant boy gets hold of some magic beans that eventually bear an enormous beanstalk that travels upward into the clouds; after climbing to the top, he encounters a fearsome giant and must use his wits to survive.
Jack the Giant Slayer takes that template and expands on it in a way that works. This isn't a disastrous rewriting (like Mirror Mirror) but rather an interpretation that strives to always remain consistent. Its central role still belongs to young Jack (Nicholas Hoult, also starring in Warm Bodies), but he's surrounded by various characters brought to life by fine actors: Ewan McGregor as the brave soldier Elmont, Stanley Tucci as the duplicitous Roderick, Ian McShane as the noble king, and more. The 3-D is excellent although not essential, and while much of the CGI looks like the same-old same-old (especially the large-scale battle sequences), the giants are an imaginatively designed bunch and the beanstalk itself is a monumental marvel.
Jack the Giant Slayer isn't close to being among the elite films in theaters now, but if your significant other or your friends narrow down the viewing options to this or Oz the Great and Powerful, best to gently push them in this direction. Oz promises to take audiences somewhere over the rainbow but fails to deliver; Jack, on the other hand, only promises to put our heads in the clouds, and that it does.