In short, Cage's character is a Precog, that is to say, he can see the future. But his specific power isn't as grand as it could be. He can only see two minutes into the future, and only the future as it affects him. Well, with one exception; for some reason, he sees a woman walking into a local dinner at a specific time. Unfortunately, he doesn't know what day this event will happen, but he is at that dinner every day looking for the woman of his future.
Not only does Cris "Frank Cadillac" Johnson (Cage) use his magician gig to get some money, but he also uses his "special talents" to win at the casinos; never anything big, just enough to live. On the day he finally meets the woman of his dreams (Jessica Biel), a nuclear bomb is scheduled to blow somewhere in the United States and Johnson is chased FBI Agent Callie Ferris (Julianne Moore) and her agency that hopes to use him to find out the location of the bomb (apparently they don't understand Johnson's limitations).
There are a ton of time-reversals and twists throughout the movie that make you do quite a few double takes (pun intended) and it's a fun ride overall. Next is one of those movies with a great, and really unique, ending that will make you want to sit down and watch it again, just to catch all the details.
There are a few Making Of's special features on the disc that are always a pleasure, but there doesn't seem to be anything about this version of the movie that makes it better than the DVD one (well besides the obvious visual quality). If you are itching for a new HD DVD, then Next is a pretty good buy, but if you are still on the fence as far as HD format is concerned, then look into the standard def version.