I’ve tried a few of these, and they are an interesting variation on the GPS theme. The plus side is that they don’t need a reviewer’s approval to place, and cheating is not allowed as your smart phone’s GPS location must match up to the Munzee you are photographing. The downsides are that they don’t need a reviewer’s approval to place, and you can’t do them off-line, which limits their placement to locations where there is a mobile phone signal. I guess there won’t be many on Dartmoor yet, although I understand they are working on making it work off-line.
There is yet another variation, called Geocheckpointing, which is geared towards taking people to nice locations, where they won’t have to hunt for too long for their find, but there is only one of these in the UK at the moment. This version of the game does not seem so appealing, and if this kind of approach is to be taken, it might be more straighforward just to have your smartphone register when you are at a location, and count that as a find. All checkpoints would then be virtuals in effect.