I have an 80DX that I use with the D100. It sseems to work the best for me in bounce mode with the difuser. In direct lighting I had problems with dark subjects. I had to photograph our chinese rosewood furniture. In matrix mode and it came out black. I had to use the spot mode and overexpose it 1 stop. The pics then came out great with these settings.
I had to do a few hundred pics for my wife while house hunting this summer. The 80 DX was left in Matix mode, with the flash set to bounce mode. These pics were fabulous! I found the 80DX had great recycle times and never delyed me. The real estate agents thought I was nuts taking so many pics. After explaining it was digital she understood.
The flash cannot do everything for you. We are photographers aren't we? If this stuff was compleatly brainless to use, then anybody could do it. I have yet to find a perfect piece of photo gear that does everything right. Perhaps that is why I have four cameras.