Our club uses them, and I think they have made a big difference.
They are incredibly easy to use. You simply push the tool into the green at about a 45 degree angle at 4 points around the ball mark - you have to push firmly -- then tap it down with your putter. They had a video for our members to watch, but it is very easy. The greens are definately in better shape -- don't know if its because more people now repair marks or if these work that much better, or both. But, we noticed a difference.