I think it really does come down to who you are. I am really a mixture of both, I have lessons, but not very frequently and I go for long periods being self taught. For me, I find that having a teacher helps focus me. Unless I am getting ready for a particular gig, I find it hard to motivate myself to really get things polished. Similarly, a teacher often helps clean up my technique if it is getting sloppy, and introduces me to new theory that I would not have looked at otherwise. I have seen great self taught, and also great players who have always had music lessons. I think though, that although you can have great players from both areas, there are many more really bad guitarists who are self taught than being taught by others I think.