As you know, I am both an online piano teacher and an offline piano teacher. After teaching extensively both ways, surprisingly, I can honestly tell you that I see many more advantages with learning online. Keep in mind however that what I just said is only true with a program that has every component it needs to give you all the advantages.
Here are the top 10 advantages of online lessons:
1. Work at your at own learning pace vs. waiting a week for another lesson assignment.
2. Take time repeating lessons as many times as you need to without paying again vs. paying for repeat lessons each time you see your teacher.
3. Receive answers to your questions as you need them through email or other support tools vs. waiting once a week to ask your teacher questions.
4. Have access to your lesson and learning tools such as video and audio vs. trying to remember what your teacher said during your lesson time.
5. You will naturally boost self disciple as you teach yourself vs. becoming dependent upon a teacher to tell you what to do.
6. You will develop your own judgment of when a song is acceptable vs. relying on a teacher to tell you if you passed. Believe me, you will be harder on yourself than a teacher is.
7. Gain solid confidence that you really do know what you are learning vs. feeling lost without your teacher as a security blanket.
8. Interact with other students through forums and blogs vs. never having a peer in private lessons.
9. Have year round opportunity to perform/express or record your songs to share with others vs. waiting for a once a year recital.
10. And finally, you can never quit online piano lessons because once you own the program you love, you will always own it and be able to refresh yourself later, or even relearn it later if you wish.
You can probably already see that the advantages of online programs are only good, if those advantages exist. So be sure to check out my series of other questions to help you find the perfect program to match your piano playing dreams.