I taught myself how to play guitar 23 years ago with a Sears acoustic and the Roy Clark Big note guitar book. I've never had a lesson, but have played with some good players and learned alot by watching them.
If you have the time, I would suggest lessons. I'm self-taught and have some bad habits that limit my playing still today. My son started playing at 12, and while I showed him the basics, I had him take lessons from a professional instructor. Now 5 years later, the kid is teaching me new stuff.
Be ready. Guitars can turn into an obsessive hobby. With the Taylor 814CE I just bought, I now have 8 guitars siting on stands around the living room.