You had me at the tag line, lots of fun and i was grinning the whole time. Gets a little complicated later on and feels a bit trial and errory but other than that really loved it.
Haha! Yeah, the "singleplayer co-op about time paradoxes and killer robots" definetly sums up the game pretty well. As for the "Trial and Error"y parts will definetly get rectified with things which make going back in time less of a hassle (think Time Forwarding, think improved Rewind controls )