I've done two mystery quilts, both by Border Creek Station.
Something to keep in mind, we didn't do blocks, we did portions of blocks, so until the final installation, we still had no clue what the quilt was going to look like. It's a lot of fun if you are willing to give up control. Border Creek Station works really hard on making a good looking quilt and then figuring out how to turn it into a puzzle to keep the mystery till the very end. Plus they give us fun recipes to try throughout the run of the quilt.
Our local shop participates so we meet once a month to review last month's installment and pick up our new one. Keeps everyone excited to see how the different fabrics work.
The first time I did the mystery quilt I used on of the recommended fabrics. It's the blue and cream one below.
The second time (just finished it!) I chose my own fabrics as so much more was needed and I love how it turned out. Our reveal party got postponed to this Saturday and I think I'm the only brown/orange girl there.
I didn't join Border Creek Station's current mystery (just starting) b/c my extra money was committed elsewhere (darn kids!!!) so I'll be missing out but next year I'll be back I'm sure.