This is going to be a negative review.
I normally love time travel films, the paradoxoi that they generate are meat and drink to me. Millenium (director Michael Anderson) from 1989 with Kris Kristofferson, Cheryl Lad and Daniel Travanti was an intelligent closely plotted examination of all the space/time perturbations and timequakes that can happen with unwonted interchange. It's worth having a look at
12 Monkeys (director Terry Gilliam) starring Bruce Willis, Madelaine Stowe, Christopher Plummer and David Morse was an excellent film also with its own attention to paradox. How do you change the past to alter the future, the very future from which you operate? Millenium recognises this in all its complexity but 12 Monkeys has Bruce Willis contemporaneous with his younger self. Can that be a good thing? It's a great picture.
Loopers is a mess designed like most films from Hollywood at the moment for boys between 15 and 22. The women in it are either whores or a madonna with a potty mouth. That goes with the demographic. Noisy, stupid, confused. Bruce Willis is implicated alas and Gordon-Levitt with curious make-up and an incipient smirk like Bruce the Younger. Not possible without reconstructive surgery.
Not a timequake, more of s fart in a biscuit tin.