I've got one. $99 at Costco. It works wonders for things like melting or defrosting. A traditional microwave at a low setting will cook the outsides of things while the inside is still frozen because even though it might only be powered for 2 out of every ten seconds, it's at 100% for those 2 seconds. When I would melt a big hunk of butter in my old microwave, I'd get really annoyed when I'd see the butter boil for five seconds, then just spin for five seconds, and so on.

Now with my new microwave, I can get really even melting or reheating, just at the expense of some time. I wouldn't consider buying a microwave without this feature.