Not directly, but heard a lot of tales about them which are unfortunately all bad, it would appear that many are a Chinese rip off of existing reputable designs which have numerous short cuts in manufacturing and many use inferior materials to cut costs.
It's worth doing a search of the forum as there were a number of threads about these heaters earlier in the year. I believe there is also a facebook page dedicated to them. People had very mixed views on them. I seriously considered buying one but eventually decided upon a Planar heater which is priced between these Chinese heaters and Eberspach (etc). So far I have been extremely pleased with it - although thankfully not too much use this summer!!
There are several facebook groups that discuss this as they are commonly used for campervan builds - chinese diesel vehicle air heaters - troubleshooting & parts sales - that may be worth a look as they are not QUITE as negative!
I have nil knowledge and are generally a fan of Chinese bits etc having had no issues, however a heater burning diesel with the possibility of carbon monoxide I would buy a trusted brand.