I'm just learning mine. I got it as an early birthday/Christmas present in October. So far I am loving it and I take a class about once a month from the dealer.
I used it for gift bags and pillow cases for Christmas. I'm also making a jacket and a mock turtleneck. It is too nice of a machine to let it collect dust on the shelf. Pfaff Coverlock 4
I have gotten a book "Serge and Merge Quilts" that looks like I'll learn more ways to use it with quilting.