I bought this wireless remote control for my Nikon D50, but it is also compatible with D40, D70, D70S, D80, N65, N75, Coolpix 8400, 8800, Pronea S, Nuvis S and Lite Touch Zooms cameras, so this little remote can get a lot of use.
This remote is battery operated, and when I got it, the battery was included with a plastic tab to keep the battery from being activated, which was nice. You can buy replacement batteries for the remote, but they are a CR-2025 3v battery, so not a standard battery you can buy everywhere. I have been using my remote for about a month now, and so far no problems with the battery life.
Although I don't use my remote every day, I picked one up for those "just in case" moments- with the price being so low, it is a great value to have on hand. I use mine for low light shots, or for action zoom shots with a tripod, because it keeps the shots from getting the bluriness from hand shake while depressing the shutter. I have had a lot of success shooting fireworks using my remote, which is normally difficult for me to do. It is wonderful to use for time-elapsed shots.
The remote itself is very easy to use- just depress the button to use it. I was surprised that you didn't have to somehow calibrate to your camera, because I am concerned that if I am nearby someone else that has a remote, what will stop it from taking a pic on my camera? While I can appreciate the fact that it is small, it is REALLY small, so I have to make sure that I don't lose the remote, which I think would be fairly easy to do.
So to recap, not something you will generally use every time you have your camera out, but it does come in handy. I also love the fact that I can actually get into my family photos easily now without have to hope everyone smiles when the self-timer goes off- I can wait and take the pic when everyone is looking their best!