If you liked Memento, you'll like this movie. The future/past loop is, as always, a difficult concept. They did a great job with the backstory, explaining how things worked, but it did leave some questions.
The cast was great, Emily Blunt plays a great part, but I think the kid, Pierce Gagnon, was outstanding. He is definitely one to watch. Bruce Willis is his usual edgy self. And they did a great job making Joseph Gordon-Levitt look like a younger Bruce Willis.
Great movie, would defininately recommend. It is a thinking person's movie, not the kick-back-and-watch-the-blood-fly movie like the Expendables franchise.