Everyone can learn to play by themselves. If you are capable of finding your own mistakes, and create exercises to improve, it's just good. However, if you have friends whom you can play with, it'll help dramatically. If you know a teacher who can teach you the things you want, it's really helpful. Guitar is supposed to be fun, so there is no reason having a teacher that teach you things you don't really want to know.
The thing is that you can't consider the teacher your only learning. Have the teacher as an addition to your learning. You know, don't just do the things you are told.
If you just play alone (like I have for a few years) you come to a point where you don't know what to do (like i have :roll
. I barely know any theory, and I don't know what I should do to improve myself technically.
What I mean to say, is that having a teacher won't immediately make you a great guitarist, and not having one won't make you not become one. A teacher can however help you getting through these points where you're not able to improve by yourself. I guess everyone reach that point sometimes.
As you probably know all the basic theory stuff, you got a good foundation for learning any instrument on your own, but a teacher can't make anything worse, so it's worth a shot.
Also, as a few others has said: if you learn by yourself, you might "grow" some mistakes that can get really troublesome later on, and can take a long time trying to get off.
