I have one of these as do some rellies we camp with occasionally. They are superb on LPG, good on 240V power and ordinary on 12V.
If you have a bit of a scout around there are a few threads - viewtopic.php?f=64&t=3038
and although this one is about the Aldi version its worth a read viewtopic.php?f=107&t=2256
I reckon they are a good thing - but you need to do good quality wiring in the car.