I'm probably the odd-ball statistically speaking in this bunch, who virtually doesn't use AF (Auto Focus) anywhere near as much as everyone else ( and who bought a K-01 primarily for video,.. )
Five out of my eight lenses are MF, and the three AF lenses are just as often used on my Teleconverter, so become MF anyway.
The AF on the K-01 has a reputation for being,.. 'underperforming',.. When I have used it with my Sigma lenses, I've found it resonably accurate in well lit conditions, but it falls apart quickly as the available light level drops, and it's waaaay too easy to end up with a finger blocking the AF assist lamp on the handgrip. (in front and below the Mode dial)
When I do use the AF, most often it's at events and parties with people, and I leave it set to Face Detect, and it's been accurate enough for my purposes in decent light.
On the occasion that I tested a new Pentax lens on the front of the camera, in the excessive light at a trade show, I found the AF to be fast and able to track moving subjects in real time with no errors.
I really think the AF used in the K-01 is 'okay' for most owners, but those of us who are more into our art and would join a forum and make posts are also more likely to speak up about issues, and more likely to provide feedback on those issues.
And yes, there have been improvements made to the AF systems speed and accuracy with each update, most significantly in the 1.03 update IIRC.
Each firmware update builds on the previous, so if you've gone from the factory 1.00 release to the latest 1.05, you've got a whole raft of changes in one hit, and will notice then performance differences.
That 'half dozen primes',.... you're going to love using them on a K-01.
And if not, you can sell them to me if they're fast primes