I applied iron on rhinestones to a quilt and here's my assessment: They were inexpensive, from JoAnn's. They worked pretty well, and the effect was great. The drawback is that you need to iron the back side of the project to get the jewels to stick, and it is hard to get enough heat through the quilt layers for fear of scorching the back side of the quilt. I still recommend the iron on rhinestones because they are cheap, and if they don't stick you can use them on something else with no loss to the quilt.
My quilt can be seen in the upcoming NWQE show in Portland, OR 9/24-26/09. It is titled "Walk into My Parlor - a Cautionary Tale." The rhinestones create a spider's web.