I bought a "commercial" type unit, locally for a lot less than the TV advertised units. I find I really like the control, and the fact it will boil water in around 2 minutes. Frankly, I usually stay with less than 50% power use, and more often in the 10-20% range.
As to the cookware, they must be magnetically reactive. Cast iron, some stainless steel and some enameled iron work very well. There are non-conductive stainless pans that don't work. Use a magnet to test the bottom of the pan, if it sticks it will work. The heating is done by "exciting the metal" with a magnetic field. The pan heats, the food heats, and very little heat is transferred back to the cook surface. After I am done and the element has cycled to cool, I can put it away. You can't do that with a hot plate until the unit is cool, usually several minutes to an hour.
I recommend the larger units in the commercial category or gourmet types, they can handle a larger pan with a large cook surface, and generate enough heat to fully heat the pan. I use a 14" skillet sometimes and it works fine, but even works better with a 7" grill pan I use for chops and steaks.
You can get a good look at what's out there at Amazon.com, but I got a super price at a local specialty store and saved the shipping. BTW even with Amazon the shipping is only about $8 not the nuwave special rate.