There have been a few rather lengthy threads about vasectomies on here already. As for me, it didn't effect drive to lift or sex drive or my auto-immune system (it was messed up before).
I do believe it has led to recurring bouts of epiditimytis (sp), although I can't prove that and there haven't been any definitive studies conducted on that topic. Then again, my vasectomy didn't go as smoothly as all of my friends' vasectomies.
Regardless of what anyone tells you (IMO), anything that alters your body is going to have some kind of effect, whether it's drugs or surgery. You just have to weigh the pluses and minuses to see if it's for you. I can tell you that it's really nice to not have to worry about condoms.