This worked fine on the D90 except you have to take it off to change the battery. I have a small hand and was able to adjust it to fit. I decided not to use it any more because with it I always had to have the camera in hand and decided a neck strap (actually, I use a shoulder strap) worked better for the way I shoot. It's a nice piece of equipment if it works for you.
I don't know how exactly a Nikon D90 might differ from my Canon 30D, but I LOVE the hand strap and would never go back to a neck strap. With the hand strap I feel like the camera is more a part of my hand and I don't have to worry about it getting knocked out of my grip in large crowds and action environments. The only time I have to mess with it at all is to open the battery compartment which means I have to loosen the screw 1/2 turn and shift it over enough for the battery door to clear which is easy as pie. When shooting on a tripod I would recommend eliminating it to go directly into the camera as it tends to shift a bit unless you really crank it on there. I will also mention it makes setting the camera down on a table a bit wobbly because it turns the flat camera base into an uneven surface so it takes an extra second to set it down carefully where any lens you have, big or small, will end up tilting down to make contact with the surface. I use a small 1" high foam pad under the lens at my workspace to keep the camera flat. But even with these small flaws, it is well worth it to me. I take shots that I would not otherwise risk dropping the camera and I'm sure it has saved me from smashing at least one lens. Plus it's inexpensive.
I have use it on my D90 for about two years and really like it. The camera feels very secure in my hand. I often will use in conjunction with a small camera case with a shoulder strap if I have need of free use of both hands. Highly recommended.
Hi Dennis, It surely works on the D90 but it gets in the way when changing batteries, not a big negative though. I would recommend a shoulder strap coupled with a waist-restraint belt instead. Keep shooting!