I'm also going to do Bonnie Hunter's Celtic Solstice mystery quilt. I like the colors/values picked and want to use some stash up--but really don't have a lot of orange in my stash so having to buy those!
I've only made one other mystery quilt--it was a workshop with our Guild. The teachers were good, the directions great. My only problem was that I really wasn't able to envision the fabric combo's and consequently not thrilled about the outcome--like the pattern, but the color I thought ws the "background" (and I loved this print) turned out to be used very little in the body of the quilt and for borders. Afterward a friend in the Guild said that she always used Christmas fabric for mystery quilts as they invariably turn out looking Christmasy no matter the pattern! This quilt really didn't have color choices inthe pre-instructions.
One thing I'm looking forward to with Bonnie Hunter's new one is that she's giving us some colors to work with.