We booked both group and private lessons for ourselves (2 adults - one of us an absolute beginner, the other intermediate to advanced skier).
The group lessons were useful and obviously cheaper, but the group sizes were large (10 people) and that resulted in a lot of waiting.
The private lessons were with Monika. She was great, able to deal with our different degrees of ability and experience, making the process of learning and improving fun. Monika went out of her way to make our holiday more enjoyable, even making a restaurant reservation for lunch on our behalf while we were taking the lift up to Dantercepies. I am sure there are other great ski instructors at this school, but we would recommend asking for Monika.
We also hired a lot of ski gear from the school, which was convenient and cost effective.