Pentax K-3: likes and dislikes??

I've had the k3 for several years now and it shares duty with the K-1 as my primary camera depending on the situation.  I really like the ergonomics of the camera - it just feels so solid and rugged like I could go anywhere I want with it if I have the right lenses (the DA*50-135 is about as rugged as they come).  There is a youtube video of a US soldier in Afghanistan who buries a k5 and that lens in the dry, dusty soil and then rinses the camera off in a shower without issue.  Of course this is probably more than what Pentax would recommend and way more than what I would every subject my camera to, but it does say a lot about the durability of their cameras and better lenses.

I also like Pentax's Shake Reduction - for low light social gatherings, macros or when I want to keep the ISO as low as possible, it helps a ton in getting sharper shots than if it didn't have it.  Of course this is primarily an advantage with prime lenses as most of the competition has VR built in their zoom lenses.  As a side note, I love how Pentax has been innovative in how they use their moving sensor to not only stabilize images, but offer things like moire reduction (since this camera does not have an AA filter for maximum sharpness), horizon leveling, astrotracer, and a minimal amount of shift capability (really helpful for architectural photography when using a tripod).  In later models, Pentax also uses their moving sensor for Pixel Shift resolution which uses the SR system to take 4 images that are 1 pixel away from each other to combine them for superior colors and higher resolution.  Alas, the k3 is one generation too soon to have that feature.

Another thing I really like is the Pentax user interface.  The button layout on the k3 is extremely comprehensive and has quite a bit of customization available.  The menu system, particularly combined with the Info button makes finding the commonly needed functions very easy to get to.  Even the implementation of the Hyper Program mode and the green button when in Manual mode where when you press the green button, it sets the camera to what it thinks is the optimal aperture and shutter speed so you can quickly establish a baseline.

Low light focusing is excellent on this camera - not many cameras, let alone in this price level, can focus at -3EV which is really dark.  Event photography is something where a camera with this capability is really helpful.  However, focus speed, especially with the DA*50-135, is not one of the strong points of this camera.  There are definitely faster focusing lenses, but even with those, it doesn't have the tracking ability of newer cameras.

All in all though, the Pentax K-3 is an awesome picture taking tool in most situations.  It is designed with a different philosophy than most other manufacturers which takes a little time getting used to.  But after using it and really getting to know it, I'm confident you'll find that it was designed by photographers, not just electronic engineers, to produce the best possible image using the technology that was available at the time.