Sigh. Time travel. A plot device that isn't used too often in movies, thankfully, because all too often it feels like it just makes things more confusing and things aren't explained properly. Or even worse, in the case of X-Men: Days of Future Past, it feels needless and unnecessary. Meet the Robinsons and Harry Potter & the Prisoner of Azkaban are a couple exceptions to the rule, which handled the time travel fine without muddling things up too much. For the most part, it's safe to say Edge of Tomorrow can be added to that very short list.
In this film, Tom Cruise (who goes by the name Cage in this film--which kept making me think of Nicolas Cage) plays a random major who gets forcibly thrust into the battlefield of an alien attack. And along with everyone else, he is killed. Except that he isn't.
He wakes up about 24 hours before his "death." And he lives the alien attack again. And is killed again. And the process goes on. And on. And on. However, a soldier by the name of Rita (or more simply, Emily Blunt) notices something is up. And she informs him that he has this ability for a reason, and that he can use it to find a way to defeat the aliens.
Since that was just about all that was revealed in the promotion, I won't say much more to avoid spoilers. What results from then on is an uncountable number of time loops as Cage and Rita work to try and stop the aliens (this is used to their advantage in the humor department as well).
What results from that point is quite a thrilling action flick that has various twists and turns to it. The time travel looping concept is actually pretty simple, as far as that goes. If you can keep up with the fact that sometimes a lot more time loops will have passed by than you realize, then you'll probably be okay. The ending is probably the hardest part to grasp, and it's rather abrupt--but it's acceptable.
Edge of Tomorrow (or Live. Die. Repeat in some cases) is a pretty exciting flick that manages to handle the time travel issue better than some others within its genre. It's not without its flaws (most namely a conversation involving someone from Rita's past that's dropped and never spoken of again), but for the most part, it's a quality action flick.