It's got a moderately tacky image. I went to high school with one
Crystal. It sort of went along with the popularity of
Kristen, and there were tons more Kristens and Kristins and Kirstins than Crystals. I like the name now, but I didn't then. I don't think it's any more tacky than
Tammy, and it's less dated-seeming than
Kristen IMO.