I just ordered one from B&H, which should be here tomorrow or Monday. I also questioned whether it was necessary. Of course it isn't, but after using the D100 a couple of times, I really began to miss the vertical shutter release I have on my F4 & F5. I would say that this alone prompted me to invest the $250 to have one.
To a lesser extent, the additional battery options will be nice for those times I'm out in the woods for an extended period of time. And because I already have a 10-pin accessory, I will get some use out of that.
I see no value to the voice recording option, as the information I'm interested in is already recorded within the image. I guess if you were the more artistic type, you could record your feelings or motivation at the time the picture was taken. I'm still trying to keep the basics straight. I'm not sure that it's important to have 50+ voice recordings, all of which say, "I sure hope this turns out."