someone alluded to the BMX thing, and I think thats the best reason to SS, a nice quiet sturdy bike to thrash the bejesus out of down or along any singletrack you care to point it at. i've been finding long gradual singletrack descents hardest because i'm sprinting like mad and can't keep it going for the whole trail.
Its harder if you try to keep up with your geared mates on a longish ride with hills, and i haven't even contemplated taking it to any proper mountains with bogs in them, that would be silly.