It could be argued that art has always thrived on a re-interpretation of classic tales. Shakespeare used widely available plots to give his view of the world. The version of Ben Hur which most of us remember is a remake of an older silent film. And of course, "The Magnificent Seven" is famously based on "The Seven Samurai," which also inspired "A Bug's Life." All of these are valid artistically, as well as financially. However, Cameron Crowe has chosen to remake an incredibly popular Spanish film, and apart from a few pop culture references (258 according to one source) has added nothing new to the experience. If this were an original piece of work, it would probably be hailed as one of the most novel movies of recent times. However, "Abre los ojos" must take that accolade, as this is the film which showed all the invention, subtlety and ambiguity. In the few changes from the original, Tom Cruise's character is made more likable and less capricious. His relationship with Julie (Diaz) is more of a relationship of equals, rather than one in which the one who holds the power uses the other.
In fact, the only reason this film has been made is that English speaking audiences will not, in the main, watch movies made in any other language, thereby denying themselves the pleasure of seeing fresh, original work by artists working outside the studio system. $60 million is a lot to spend just so people do not have to read words instead of hear them.
So while there is nothing wrong with Vanilla Sky, do yourself a favour and check out the source material.