I found the film Primer quite lacking in many respects
It's said Primer is a "thriller," to which I laugh. It is most certainly not a thriller in the exciting Steven Spielberg sense of the word.
Dull, boring
The majority of the plot involves two scientists, Aaron and Abe, trying to figure out what is going on. And by the time they do, they've screwed things up for themselves.
Unfortunately, Primer lacks interesting events. If you're going to have time travel, you should have at least one alien race with a new type of forehead wrinkle. Come on Hollywood, give me something I haven't seen before!
Comparisons
Obviously there are many excelent films which involve time travel, such as the Terminator series.
Many unforgetable Star Trek episodes involve time travel. We find examples of this in both Star Trek IV: The Voyage Home and Star Trek: First Contact.
Does Primer compare to these? I think not. Even the worst episode of Star Trek: Deep Space Nine is worlds above Primer in almost every respect.
Conclusion
Rather than further deriding Primer for its obvious flaws in these concluding remarks, I would like to extend a "bravo" to writer/director Mr. Shane Carruth for at the very least attempting a film in which time travel is taken very seriously.
Better luck next time, Shane. Let's hope your next film is less dull.
Primer
Year: 2004
Director: Shane Carruth
Writer: Shane Carruth
Cast: Shane Carruth, David Sullivan, Casey Gooden, Anand Upadhyaya, Carrie Crawford
Decker's rating: ** (two stars)
Wed, 2006-10-25 16:02 
Ah yes, but is it worse than "Spocks Brain"?