If you've seen the trailers for the movie you know the premise. In the future (which is 60 years from now) they invented time travel and made it illegal so only criminals use it. The criminals use it to dispose of people they want killed. For reasons hardly explained, just stated, it's difficult to get rid of bodies 60 years from now. They hog tie and hood their victim and send him to the past (which is the year 2044, some 30 years in our future) and have someone prearranged to kill him
The movie was pretty good. I hadn't read any reviews prior to seeing it but looking it up on Rotten Tomatoes, I see it's got a 94% rating. Pretty good for sure. But if you go there are several things your going to have to deal with:
1. Why don't they just kill the victims in the future and dump them through the time machine in the ocean? I can think of several plausible science fiction reasons why, so just let it go.
2. How in the world does Joseph Gordon-Levitt turn into Bruce Willis in 30 years? Nothing plausible comes to mind.
3. Why do many of the vehicles in 2044 look like 2012 cars with solar cells and weird hoses all over them? The year 2044 appears to suck big time. I'll be 93 by then so maybe I won't care.
4. Time travel? Go with it.
The central theme of the movie is the difference betwee what motivates Joe and Old Joe. They can't understand each other because a gulf of 30 years lies between them and they are not the same person. Joe doesn't really care about the future. In a voice over early in the film he says people with long-term vision aren't likely to become loopers. Old Joe looks at his past self and can't believe he was once such a shallow jerk. But the longer Old Joe survives in the past, the more uncertain his past (in the future) becomes and the less sure of himself he becomes.
The best line in the movie is when Joe and Old Joe are really meeting for the first time and Joe wants to know what's going on. Old Joe (Bruce Willis) says some thing like "To tell you that we have to talk about time travel. If we talk about time travel we'll be here for hours making diagrams on the table with straws. So let's not talk about time travel".