I liked the alternate ending better. It made more sense and was clearly the intended ending and not the crap ending they used in the theater.

The alternate ending had Will Smith giving back the creature he had captured to experiment on and the creatures let them go and live. Will Smith had come to the conclusion that while the virus might have turned everyone into these creatures, over the years they have become more than that. They have feelings for each other and a social existence and he goes around hunting them during the day when they sleep. In a sense he is a Legend to them just a Vampires are legend to us. He hunts during the day just as a vampire hunts us during the night. This is something that is unstated in the alternate ending but is clear that was some of the intention and thus remains truer to the novel to my understanding.

That explanation aside, I would not like to see a sequel to the movie...that would suck and would be dumb. Will Smith is dead and if you used the alternate ending, I think they came to the conclusion that they would live in isolation away from the creatures instead of trying to cure them.

A prequel would be awesome. I think the story of what they were doing and how everything got so out of control could make an awesome movie. It is kind of explained through flashbacks but I think there is more of a story to tell and that it could be very interesting.