Pentax has even provided an adapter ring for mounting optics K.
Two complaints:
1) the lack of additional dedicated flash more powerful than the built-in flash to unclog against-days or take pictures indoors. I purchased the flash Pentax AF-200FG, the smallest model in the range. Mounted on the Pentax Q, THE FINDINGS them are excellent, but the size of the flash requires its offset on a carrier strip flash and therefore the purchase of the appropriate connections.
Another advantage of a separate flash: besides power, it does not use the device battery, thereby extending battery life.
2) autonomy: too low. A backup battery is essential. Why not plan a rechargeable battery to be fixed under the sole of the case. But now I'm a little too demanding no doubt.
Apart from these two reserves, the use of my Pentax Q gives me great pleasure. And if like me, you become a fan, enjoy discounts. I bought a second with 5-15mm zoom / f2.8-4.5 for under 200.