I know someone who bought one and sold it less than a year later. He then bought a road bike.

No problems with it as far as reliability goes. He wasn't using it aggressively--not much skidding going on here. I'm guessing the whole novelty of it did fade, since he replaced it with a road bike. That said, it's not because having the gears wasn't useful. He just put it this way: "if you want gears, get a road bike."