Good: (1) Playing has never been easier to learn. There's hundreds of sites devoted to teaching guitar. (2) Books can't answer questions like knowledgable people can. I mean, look at this forum!! If you have a guitar related question, you're not limited to the people around you. You can throw out the question and have people from all over the world put in their opinions. (3) I would have never even heard of half the musicians whose cds I now own if not for the internet. I rarely buy cds unless I know they'll be good (used to be by word of mouth), but now I can listen to clips of songs, and I have bought many albums from what I've heard on the net even though no one around owned the album. (4) The internet offers a way for people to get together who may have never even met otherwise. I'm now friends with many guitarists in neighboring towns that I met through the net. I could go on, but for demonstrative purposes, I'll move on to the negatives.

Bad: (1) New musicians now lack the ear training that comes from sitting down and learning a song by ear. They can read tab decently, but it's harder for them to improvise or catch on to a song that's not tabbed out (such as in a live situation).

Conclusion: The internet is a GREAT advancement for disciplined musicians. The pros totally outweigh the cons.