And then the flash had arrived as i came home from work

(YN-560 II)
I can say that it works perfectly on my K-5 mounted in the hotshoe. With 40-50 tries i did not have any misfires or problems at all.
The quality is really great, and delivered in a nice "soft-case" for protecting the flash when carrying it around.
I have tried different output levels (1/1, 1/8, 1/16, 1/32, 1/64, 1/128), and it also keeps up with the K-5 in continuing shooting mode fine, when the power is dialed down.
I'm impressed with the recycle speed too.
When it's put in S2 mode, it even ignores the preflash from the onboard flash, and can be used as remote slave
All in all very happy with the purchase, and i'm looking forward to use it "for real"