I've got a few skins that i use sometimes, mostly in a hammock which avoids the issue with comfort that Martyn mentions. When we're all camping as a family we tend to use bigger airbeds and they can be a bit cold in the Autumn/winter so skins on those work well.
I do like having one in my chair when sitting around the fire to prevent a warm front and cold back, if you get a nice big one (or sew a couple together they can completely cover your back onto your shoulders, lovely and cozy. But they do shed quite a bit which can can get everywhere, we don't elt the kids play with them in the house any more
You need to treat them with respect as they're not great at getting wet but they're not going to suddenly fall apart or anything, I had about 20 here once and they were all soaking, gave them a good hang and they dried out fine, the siliconeised ones are more resistant especially when it's in contact with the ground or a damp surface.
Over all i'd say they're quite tough, they're not spongy comfortable in any respect and they're bulky so choose when you use them...like i said, good in the hammock.
And kids love them
Sheep skin is quite good, a little more cushion, generally smaller (need to sew a couple together (easy to get hold of from Ikea
) and best of all you don't get the shedding of hair making them more friendly in that respect.