Summary: After sending the first unit back I got the second one to work w/ my D90 only through sheer persistence and McGiver inspired creative ingenuity. The unit would make electrical connections when it was loosely screwed in but as soon as I tightened the the thumb wheel connections would be lost and the LCD display would go dead. So, I decided to try adding spacers / shims between the battery pack and the camera body.
Outstanding Grip! (Just not sure the extra stuff is worth the extra $)
Bob Tobias "Robert Tobias", Amazon
20 December 2009
Summary: This vertical grip is surprisingly well built. It makes a solid connection to the camera (in my case a D90 but it also works with a D80). The controls have a solid feel and there is a certainty when you push a button or turn a dial. The rubberized panel adds to the solid feel and provides a bit more "camera to hold on to." This is especially important if you are used to larger SLRs (e.g., D200).
Summary: This battery pack helps me with my D90 in two ways: I have big hands, so it give me more to hang onto, and it makes shooting in portrait (short side up) much easier because duplicated shutter release and controls are accessible in the same placement as on the camera itself in landscape orientation. The extra battery space has not been that big a deal for me as I never go so long that it might be a concern, but it's nice knowing it's there.
Summary: The MD-80 is easy to install and use. I like it because it doubles (or more) my time in the field shooting. No more battery worries. And the extra controls allow portrait-format shooting more comfortably than having to roll your hand around to the top. One thing I don't like: When you install the MD-80, you have to remove the battery hatch cover from the camera, which is easy, but there's a slot on the MD-80 to store the cover and it rattles around annoyingly in there...
Pros: Easy To Install, Good Value, Long-Lasting, Reliable
Summary: I really like having the extra battery time (especially when I use the GP-1) as well as the extra balance it gives in my hands but if you have small hands like I do you might find it difficult to hold comfortably.
Summary: Although orginally desgined for the D80, the MB-D80 Battery Grip works great the D90. The two biggest advantages of getting a battery grip are: 1) to counter balance the weight of you "pro" lenses and 2) not worrying about having to switch batteries in the middle of a shoot.I've used a 3rd party brand battery grip with my D40X, as well as the [...] battery grip when borrowing my friends' gear... and I have to say that this is the most natural feeling grip by far.