I am generally a movie curmudgeon with a high bar. I got it as an iTunes rental for a long flight. iTunes only gives you 24 hours once you press play. I watched it three times before expiring.
Cool, agree on the first two, will have to rewatch Sneakers, haven't seen Primer. Here are some of my favorites: Kramer vs. Kramer, High Noon, Groundhog Day, Leon: The Professional. High Noon in particular is told in real time so it has this intense feeling like Whiplash.
Sneakers is wildly entertaining on many levels. Plus it was an early hacker movie which was cool. Primer is trippy, one of those rare movies where you will instantly watch it again after the first viewing. Then you'll google the plot and read for an hour and watch it a third time in the same day. It works though.
Primer is the best film featuring time travel that I've ever seen. And yes, the plot is highly convoluted, and there is virtually no explanation. Also, it was filmed on a very low budget, and some of the key dialog is hard to understand.
Primer was great! I liked the gritty, detailed, realistic but fictional engineering in the story as much as anything. That aspect reminds me of the Neill Blomkamp films - District 9, Elysium, Chappie.