Many people are searching for online courses to learn the guitar because they are often very cheap compared with local instructors paid by the hour and other benefits. You could find a high quality course with many DVD's created by a world-class instructor who charges very little comparing to what your local teacher would be charging you by the hour. Even your local teacher could be very limited and would not teach you advanced lessons, so if you want to learn the guitar from beginner to expert, saving a lot of money in the process, the Internet is clearly the only way that makes sense. Learning from a book is totally prehistoric.
You will learn much more easily with software or DVD because of the interaction with the teacher. Although he wouldn't interact really with you, you could always pause the DVD to replicate things that where taught and learn at your own pace. It is unlikely that every people will feel good about learning from his PC. Older people reject many things that are built without interaction with another person and in this type of courses you don't have immediate interaction. Although some courses do have a members only forum in which you can get an answer fast if you post a question there (in some cases, even the creator of the course is an active member of this forum), for older people this process could seem a little "cold".
Playing guitar lesson in front of your PC is something weird for many people, but watching professionally mastered DVD's with detailed lessons, while drinking a cup of coffee is definitely much more comfortable. With either option, you wouldn't get embarrassed if you fail in any lesson because you only watch the DVD's or the software. Definitely, one of the worst things about purchasing an Internet course is that you will hardly find excellent lessons for very advanced students. This is normal because your local guitar instructor wouldn't teach advanced stuff without you paying hefty fees.
Also, because demand is low for very advanced lessons you wouldn't find many quality instructors interested in teaching this kind of stuff. Although few people will prefer "personalized" lessons and will not be comfortable learning from their PC or watching a DVD, most people are very satisfied with this kind of learning, as it shows the majority of posts left in one of the guitar learning courses available on the Internet. The forum is somewhat like a classroom where you can interact with other people more or less in the same way. In the case of this course, the creator of the course himself is an active member of the forum and answer questions from students.
Andres Berger enjoys helping people to learn to play the guitar. He writes often about the steve krenz guitar course so people could decide if is the right choice for them.