I have enjoyed the few mystery quilt alongs that I have participated in...a couple of BHs, here on the QB with Paintmejudy and a couple others. As Pamela posted, mystery quilts often challenge your skills and teach new tricks and techniques. I love expanding my quilting skills.
This November I am participating in a Mystery QAL hosted by Irene from the Netherlands, her blog is Sugaridoo and it is being sponsored by Bernina. I just picked up my colorful fabric yesterday.