I can't comment on the failure of the heating unit other than to say I've had mine for about 3 months and used it daily with no problems. 3 months isn't too long though so that's not much of a testimonial. As far as inability to evenly vaporize I've never had a problem. After a couple of hits I stir it up and take a couple more hits and it works fine. It takes a few tries to figure out the right heat setting and how fast to hit it. Too hot and/or too slow and you can burn the weed. After a couple of times even a stoner can figure it out though.