The Pentax K-01 delivers good image quality due to its 16-megapixel APS-C CMOS sensor, and offers great value if one considers the fact that it's the only mirrorless system camera on the market that can support an existing DSLR lens lineup without the need for adapters. The build quality is good and feels premium in one's hands, and the AF system is generally quick and accurate though there were random occurrences where the AF would take a little longer than expected. The large dials make it easy to operate the camera, while the menu system is simple to use, thus if you're upgrading from a simple compact camera, the process will be less intimidating with the K-01.
However, the weight and heft of the K-01 may turn off those who are looking for a backup camera to their DSLR as the K-01 weighs almost as much as an entry-level DSLR. It's heft might come in handy, however, when an equally big DSLR lens is mounted on the body. While the design of the K-01 is unqiue, it may not appeal to everyone.
With a retail price of $S1,099, the K-01 costs more than an entry level DSLR body from competitors. With that in mind, it doesn't really make much sense to pay for a mirrorless system camera that not only costs more than an entry-level DSLR, but is as bulky and weighs almost the same. For example, the Pentax K-01 tips the scales at 479.1g while a Canon 550D entry-level DSLR body weighs 475g. In fact, the K-5 DSLR model from Pentax weighs 544.3g, which isn't substantially heavier than the K-01.
In the end, the K-01 feels like a camera out of place. Users who like the idea of being able to mount K-mount lenses are probably more advanced users, and they may find the manual settings and controls lacking on the K-01. Those who wish to upgrade from a digital compact may find the added bulk a drawback, when compared to the slimmer offerings from other mirrorless system cameras. As much as we understand why the physical aspects are such for the K-01, it is also its undoing. So while the K-01 is a pretty good camera when it comes to performance and hardware, we can't really seem to figure out just who the camera is for.