I hate the 110 format, but I always thought if I had to use it, this would be the camera to have. I don't know this for a fact, but I suspect that Pentax did it as a way of proving that they could do it.
It's a remarkable camera. Most 110 cartridge cameras are little more than box cameras. This one is a true single-lens-reflex (SLR); with interchangable bayonet-mount, focusable lenses; a detachable flash; and a detachable auto-winder. The only concession Pentax made between this and their full-size cameras is that this lacks manual exposure controls.
Modern Photography magazine wrote a big test of this camera and a couple of the lenses. I was surprised to see that the lenses tested Excellent for resolution (but didn't do so hot for contrast).
Picked mine up for $8 from a thrift shop, and it's jammed with the mirror up so I can't look through it. I've had it partially apart but haven't been able to free it up. Maybe someday. Still, I'm very impressed by it. If I could still get 110 film and have it processed without paying a mint for it, I'd consider trying it out.