Fantastic pack, stuffs up in almost nothing. Great to throw in your larger pack for walking around when traveling. Also, fits perfectly in a bike jersey pocket for picking up groceries on the way home from a ride without having to carry a sweaty pack through your whole ride.
Careful though: put a DSLR and a lens in there without a rain shell or something as padding and it's gonna jab you in the back all day. Would be perfect if it had a little more structure to it when in use, but that's the trade-off for portability I guess.