Just saw a preview of Safety Not Guaranteed. It's the perfect time travel movie for people who have no or next to no interest in time travel. It will probably play almost as good at home as in theatre. Works well as a comedy drama but not at all as sci-fi. It's not a bad movie, don't get me wrong, despite a few logical flaws and a few questions that probably should have been answered, but it is a bait and switch movie, and your enjoyment will probably depend on your enjoyment of the switch. I did like the switch but I liked the movie I was expecting a bit more. In contrast Cabin in the Woods was mostly up front that there was going to be a switch of some sort and boy was it a great one.
Now don't get me wrong: I don't think that lots of special effects would have worked for the movie it had the potential to be, but I think you could have done a lot with a few pyrotechnics and clothes of the recent past and covered similar ground that it did in far more interesting ways.
Looking online I do seem to be in the minority with my views: I do think it's a sweet movie and I enjoyed spending some time with these characters. I just wish they had either done more with the time travel aspect or jettisoned what there was of it completely. I won't say if the characters actually do go back in time or not, but I will say that the time travel (real or imagined) is of lesser importance to the story.
One other quibble: a potentially interesting sub-plot ends in a way that might be true to life but which is dramatically unsatisfying.
So... marginal recommendation. Reasonably well crafted, well acted, wouldn't mind spending more time with the characters in a different movie, but not entirely satisfying.