My son made leaps and bounds in his swimming progress during the 12 classes. He didn't quite make it to getting back to the side of the pool by himself, but that is largely because he is very stubborn.
The instructor, Kimberly, was great. She was very patient and good at getting my son to try new things (which he does not like to do).
The classes are expensive but you child does learn the full class instead of one-fifth of the class if there are four other kids in the class. I think that makes it a decent value, but the financial commitment is still significant.