Have had ours for some years now and have cooked alsorts on it. everything from the morning fry up, burgers/sausage for lunch, cake for afternoon tea, a nice roast for dinner, and allowing the coals to burn out naturally, it really takes the evening chill of the tent, while mulling some wine.
since we had ours, the Hairy Bikers were 'invented' and quite often use one to cook on (more so in earlier series). It even got a good review on the Gadget Show not so long ago.
Have not used cobblestones, but do use Australian Heat Beads, which to the untrained eye look like 'normal' charcoal briquettes, but are more dense therefore burn hotter and longer. to cook for day in a similar way as I mentioned above, would only use a dozen to 15 briquettes! Once you have finished cooking one meal, just drop the fire basket in a bucket of water, to put it out, then once safely out, allow them to dry, and reuse them later on!
yes they are a bit of a large outlay, and we really thought long and hard about it before buying one, but in all honesty, wouldn't be without it now either at home or while away camping with the family.