I haven't used it yet but overall it seems like it is reasonably good quality.  However, when it arrived it was completely filthy and incorrectly assembled.  If you purchase one of these make sure to open the box outside because the very fine and gritty dust from the rocks will be all over it and it will get everywhere. After cleaning it up I discovered that the bottom heat plate was installed incorrectly, so I had to disassemble it and reassemble it correctly.