I have seen Dark city on my torrenting sites and I never snagged it. Cover didn't look appealing. The butterfly effect isn't that great and I'm sure the sequels are worse.
I have to say butterfly effect is one of my favorite movies. I just love the idea and i think they did a good job at portraying different possibilities, although some were exaggerated but it was still an interesting movie, some of the sequals i wouldnt pay money to watch, but ive seen them all