I basically gave up on caffeine almost a year ago. I've not noticed any overall changes, aside from not having an addiction. There is one short-term benefit that regular users seem not to have - if I've had a very late night or for some other reason I'm very tired but I need to keep going, I can take some caffeine and run normal(ish) for several hours. It's saved me a few times, I'd be disappointed to lose that tool.

I do miss the taste of coffee though.