I just had a puncture. It was on the edge of the tyre tread, near the wall. No amount of tyre sealant would have helped. Had I not had my spare, I would have had to be towed back home (no local tyre places had the ps2 in stock, only ps3) and then paid a taxi to get to work and back. It would have cost me more than if I hadn't gone in.
That spacesaver helped me out but life would have been sweeter if I had had a full sized rim.