I've only ever been inside one of these things... on the Southern Upland Way... but as it was halfway through a day's walk, I didn't stay there. Earlier, I'd met an American couple, inveterate wild-campers, who had stayed there rather than stay in their tent. Anyway... if one of those places turned up towards the end of a day's walk, I'm sure I'd happily use it instead of the tent... but I'm not expecting such a scenario to present itself any time soon.