I think this depends on where you're getting your lessons and how much you're willing to pay for them. While in-person piano classes are ideal, because a child can interact with his or her teacher and is less likely to be distracted, it's hard to discredit online courses and lessons plans as well. Simply put, not only are online piano classes convenient, they're cheaper too. A great example of this is PiaNote's online piano course. For less than $200 for the entire year, you are granted access to countless hours of piano learning videos. You can even interact with various instructors as well. So, yes, taking piano classes is worth it so long as you find the right piano class for an affordable and worthwhile price.