IMHO of course
'Primer' is a movie made for geeks, by geeks, on a budget of $7,000!! Not much for special FX, but very fun plot twists and paradox-related thought exercises. Loved the dialogue, the directing, everything. A must-see for any sci-fi geek or indie-movie fan.
They spend 1/3 to 1/2 of the movie just developing the mostly-accidental invention of the time machine in a garage, the amazing thing is the way they develop it makes it somehow strangely believable, not the least of which because also once built, the characters do the first thing many would try with such a device.
And of course, reality starts to come increasingly unglued as the story goes on and the ending is great but you'll want to go back and watch the final 20 minutes 3 or 4 times to unwind it all in your head.