Engadget has published a lengthy review on the Pentax Q that confirms what many people have assumed since the camera was announced: that using a tiny sensor just to make an interchangeable camera system small isn’t a good idea:
Pentax really has managed to design the world’s smallest interchangeable lens camera — and yes, it does work. But there’s no magic at play here. The Q is small because all of its components were downsized — Pentax took everything from the lens to the image sensor to the mode dial and shutter release and gave them the shrink ray treatment. [...] The result is an attractive, pocketable ILC that doesn’t quite follow its powerful pedigree.
[...] If money is no object and you’re not keen on capturing incredible images and video footage, then perhaps you’ll still consider picking up a Q. As for the rest of us — we’re perfectly happy with our larger, much more capable ILCs, and wouldn’t dare consider making such a sacrifice just to carry a bit less weight on our shoulder.
There’s a ton of competition in the mirrorless camera market now, and one of the big selling points is having a DSLR-caliber sensor in a compact camera body. Lose the sensor quality, and there isn’t too much of an advantage over all the other options out there.
Pentax Q interchangeable lens camera review [Engadget]