It's not Nolan's best, and I'm not sure it entirely makes sense. But it was better, and easier to understand, than I'd been led to believe. Of course, I was watching it at home, with subtitles on, so that always helps with making out mumblecore actors.
But the time-flipping: I realise it's well thought-out, but I'm not sure it's quite well thought out enough. A second watch might give me clarity on that, but unlike say Interstellar or <Inception, I don't think I'd particularly want to watch this again any time soon.
Which, since I'm realising that as I write it, surely means half a star off?