I have one. I stood on the sidelines for years and watched people argue for and against on the Fine Woodworking online forum. I got mine off the local CL for $275. Although I was skeptical, it does a really good job with woodworking tools; chisels and plane blades. It offers consistency and gives a very sharp edge. I had heard that it was slow, but I haven't found this to be the case. I thought the honing wheel was a gimmick, but I can take a blade that's slightly dulled, run it over the honing wheel for a few seconds, and get back to work with a sharp edge again.
I have the knife jigs, a scissors jig, and the truing jig. I've found it easier to sharpen knives freehand, but the scissors jig works pretty well. I think the price for a new one is outrageous - if you can find a used one, go for it.