i've been. there is a topo in the vallee du grife guide. however i found it hard to work out where the problems went even with the topo. its a series of caves at the bottom of a huge cliff,stays dry in the rain.it might be a bugger to find without going with someone whos been before.
the rock is a sort of sandstone conglomerate and i imagine its an aquired taste.my mate who lives about 5 miles away from the crag would drive 40 miles to the wall in preference to climbing there.