Online (Skype) lessons
This kind of online lesson has many similar benefits to real face to face lessons. You get the same real-time question/answer and demonstrate/explain progression. The best thing about learning via Skype could be that you don't need the tutor to be local.
You could be on opposite sides of the world, in different time zones, so fitting lessons into your schedule should be easy. Skype lessons tend to be slightly cheaper too because there is no travel involved for either person. The tutor can take on more students and afford to charge a little less.
Anything based online is reliant on your internet service provider. While it may be a rare occurrence, your service going down tends to happen at the worst possible times — no internet, no lesson.
Sound quality is another issue, no matter how good an ear the tutor has, listening via Skype isn't the same as being in the same room.