A couple weeks ago the LA Times took a bunch of teakettles - electric and otherwise - out for a spin. Read what they had to say here.
After wandering off to another room and melting his last teakettle (oops!) Tea Guy, for some strange reason, still clings to the stove-top type kettle, a cheap ten-dollar job with a copper bottom that actually does the job quite nicely.
I'm not sure why this is, since I have a nice electric model from Adagio that is clearly superior. I think it must be a combination of inertia and a temporary lack of counter space. One of these days I'll get with the program.