There have been probs with the Nikon stuff too, I use it. However the best thing is to learn the equipment and don't rely on TTL or automatic. As long as the flash is on manual and you are working the camera adjustments along with the flash output you should always have consistent results, be they consistenly bad or good. What ever they are, they are what you decided and not what the camera or flash thought you wanted.

Once you have mastered manual flash setting then you can begin to experiment with auro and TTL settings. I've found you never get consistancy with any auto or TTL settings, there is always something that will come up to throw off the flash brain in a lighting situation.