I have that bucket heater (ordered from Amazon in mid January '12) and I absolutely love it. I mostly brew from my garage now and don't have 240V there, only 120V/15A. I first used this device during the winter and was able to get a rolling boil on an electric stove by dropping this in the wort and turing the stove burner to high. I use it to heat my water and it is most helpful when used in a kettle that's on a burner - the time to reach a boil is greatly reduced.
Regardless of what others might say, I have used this device by itself to actually boil wort. The problem with that is that the device has a safety switch that will turn off the element when it has been at boiling temp for a few seconds. What happens is that you'll reach a rolling boil for about 10 seconds, then the device will turn itself off for about 5-8 seconds. The batch that I boiled with it isn't ready yet, but I haven't detected any problems (YET, yes, I know about DMS, we'll have to wait and see). For that batch, I just placed the kettle on the propane burner and dropped it in and waited. It certainly isn't quick to boil by itself, but it allowed me to walk away rather than babysit the burner.
Hope that helps,
Isaac