It looks quick-paced, the plot seems interesting and the makeup on JG-L looks really good, allowing you to believe that he really could be a younger version of Bruce. From the reading I have done, Joseph spent a lot of time getting his vocalizations in tune with Bruce as well. I guess we have somehow suspended the concept of paradox though, since if Joe actually goes through with the assassination, then the older Joe would have that memory and would know how it all went down... at least until he tries changing it.
What a mess that could make of your mind.
If you want to see Joseph Gordon-Levitt (yes, he's that kid from "3rd Rock from the Sun") in other works, he is great in "Inception" (brilliant film all the way around really). You may also remember him from "10 Things I Hate About You", which is a cult classic. "(300) Days of Summer" wasn't bad....I loved him, but wasn't so thrilled about Zooey Deschanel in that one as she was just a bit too over-the-top odd. "50/50" is a recent release and it was very good.... you know an actor has nailed a character when you find yourself sobbing at the movie and wishing with every fiber of your being that the guy makes it. Warning though, Seth Rogen is his usual crass self in the film and there is a sex scene, so you may want to find an edited copy.... oh, and Anna Kendrick always seems to play the exact same monotone character... its more of the same here, but somehow this time she's almost likeable that way. I will add one more warning for anyone who has had cancer effect their lives...this movie will be hard for you to watch. Oh, he'll also appear in Christopher Nolan's "Dark Knight Rises"...there is a rumor going around that he's being primed to be the new Batman should another director choose to step in and continue the franchise.