My main flash at the moment is a Sigma EF-530 DG Super. I've always struggled with how to get consistent results with it. I'm sure a lot of it is (still) user error, but I think that says something about the current state things in the Pentax flash world.
I just received a Pentax AF280T in the mail. I'm impressed. Simple to use and consistent. It's pretty compact, has tilt/swivel, and seems powerful enough to get the job done.
A quick search on the Internet resulted in:
Put the camera in Tv or P mode and the flash in red/green auto mode.
In Tv mode, use the ISO and/or exposure compensation to control artistic aspects. For example, changing the ISO will make the aperture change. Changing the exposure compensation will do similar and allow for intentional under/over exposure.
It is simple.... and it works. I've only taken a few shots, but they all turn out properly exposed and looking good. (although I'll be curious to see how my stofen diffuser on order will change things).
I think Pentax should re-release the AF-280T with improvements like P-TTL (HSS, Rear curtain sync). If we can't have TTL, they should at least offer the awesomeness that is an auto thyristor flash!