God, everyone being immortal, or just some people, would be terrible. If all the idiots of the world chose to be immortal, their stupidity would probably flourish and the world would end up in the shitter. IF we had such a technological advance, it should be reserved for the wise and great teachers, so that they could help future generations (and also the people who created immortality...). If we still had great minds like Davinci, Einstein, or gary coleman around, the world would probably be a different place.
also, overpopulation anyone?
However, if there were some sort of immortality created virtually, this could be interesting. Assuming we were on some sort of network where we could do mostly anything reasonable on a whim and have no physical restraints, that could be fun. I would be more in favor of a longer life span, say 500 years, as opposed to just immortal, because i seriously don't believe i would be happy about being alive for thousands of years on an overpopulated planet with nothing new to do.