I have the F100 with the MB-15, so getting the MB-D100 for my D100 was a no brainer. I'm not sure about the rest of you guys, but mine fits to the body so tightly, it's tough to get off! I love the vertical shutter release and the fact that it also has the main command dial right there too (the MB-15 doesn't). The extra batteries are a big bonus, plus the fact that I have the SC-17 10-pin cable release that I use all the time.
Also, I put Energizer Photo Lithium AA batteries in the camera and they are still going strong after over 500 shots and numerous forays into the menus. If you go out and buy Wal-Mart NiCad batteries, don't expect them to last very long, but you shouldn't anyway!!
I would suggest this grip to anyone who owns the D100!