I have had a BlendTec for 6 years now and it's hands down the best thing I ever purchased for my kitchen. The BlendTec is pretty comparable to the Vitamix, they are basically direct competitors.
You will be amazed how over tim you find yourself using it for things you either never thought to do, or puled out other things to do.
As for comparing to regular blenders, there is no comparison. Regular blenders just mix stuff up and make relatively small chunks out of it. You could run it for hours and it would never get as smooth and creamy as something run through a Blendtec for just a few seconds. It's like trying to compare a bottle rocket to the space shuttle.