1. Unacceptable prolonged shutter delay in P-TTL mode:
http://www.pentaxforums.com/forums/172-pentax-k-3/242556-k-3-delay-when-using-flash.html
Some K-3 users reported that the delay was particularly long, noticeably much longer than that of the K-5, which was not that noticeable.
Another thread at the Taiwanese PFC Pentax forum also states the same thing:
http://www.pentaxfans.net/thread-143957-1-1.html
(in Traditional Chinese)
A petition is being raised.
2. EXIF is not stored correctly for whether the flash is turned on or off:
http://www.pentaxforums.com/forums/172-pentax-k-3/241800-k-3-flash-issue.html