Personally, I find it to be a huge p.i.t.a!! You have to really "pounce" the chalk onto the template and when you start to sew, the chalk comes off and the lines are so light you can barely see them. I am using it now on d-i-l's dark purple quilt and it shows up great until I start to quilt then slowly vanishes. Could be because I'm left handed, or maybe not. Anyway, I usually wind up tracing the design with a water soluble quilters pen so I can see the design.
Oh, and the left handed remark is because I hand quilt.