me ive had both. im mostly self taught and i have been going to lessons for almost 2 years now.
the biggest difference between the two is where your focus is. when you teach yourself its hard to keep you brain o0n the hard things when you hear/see something you really want to learn or you think you can do. a teacher can help keep you going through the tough stuff and take care of your questions when you get stuck.
when i started playing i didnt know a thing about the net, i learned by watching my friends play and asking questions about things i saw, and that is still one of the best teachers you can have. but this site can really help with lessons, pm to the teachers, and even just asking around on the forums.
just find your groove and go for it. if you have any questions just ask.
They say the END is near, but I'm Tired of waiting.