I don't see why the great reviews. The actors did a good job of making it believable they were the same person at different ages. The plot had character change, but virtually all plots should. Beyond that I was not that impressed. The premiss just made me say why?
Why if time travel was outlawed, did only organized crime have it, certainly the government had also.
Why send people back 30 years, how about 100, 1000, one million?
Why send people back to be killed because it is hard to hide bodies, why not kill them and send them back dead, gets rid of the body and eliminate the need for loopers.
Why send them to the middle of a corn field, why not the middle of the ocean? Dead or alive you wouldn't need loopers.
Why make the lame 70 telekinetic mutant a key part of the plot?
Why at the end didn't the time line loop back to the beginning, like the first time he fell and died?
Why did the older character go back in time with the hood on once?
Why did I waste my time when I know Hollywood can't do a time paradox correctly?
Finally, the logic of the young character's seeing the loop is flawed. If his assumption that his older character killing the mother caused the Rainman to be evil and send all the loopers back around the same time, then not killing the mother would have changed when he was sent back and he never would have been there to kill her to start with. So either the whole movie is like the dream season of Dallas, or the kid would become the rainman either way and the older version of himself was actually correct.