I bought one of these a month ago at a B&M as they were on clearance. I don't like the pipe, but the keystones really work well. I have dropped a few of the stones in a briar and they do the job well. It helps when it is super humid out where I am.
The one thing I noticed, however, is that the keystones do change the taste of the baccy, but not in a bad way. I notice the most change in an aro. I think this is because the stones absorb the flavors from the smoke more. However, after about a half bowl, the flavor is not absorbed as much and can actually get to the ole tastebuds in mostly full force. I prefer to use the stones on straight (non aro)blends when ambient humidity is a problem.
As far as the pipe, goes, I think it is fine for a beginner, but I really don't like the fit or idea of the plastic base and stem. I much prefer my briars and good ole vulcanite stems. The pipes are light though. It makes a great beater pipe, and the base is easy to wash out with hot water, making cleanup a snap.