The roll I tried was Kolor, which causes your images to have a random color gradient. Under and overexposure change the way the effect shows up on the negatives. I'm not usually a fan of crazy effects on film, but this was kind of fun. Next time, I'll definitely plan for overexposure, rather than shooting at 200.
I've also got a roll of 600nm, so I'm excited to see how it differs from the Kolor. Snag some, and a sweet cat calendar, here.