I have had a D200 since 2006. I use three Nikon batteries in rotation. While I have heard the horror stories about battery life, I usually get at least two days carry and use out of one charge. Someone posted that the camera "sleeps" automagically so I rarely turn it off.
Nikon worth it? Who knows, but after paying for the camera, it did not seem worth skimping on something as inexpensive as a battery.
All of Johnny's tips are good.
Great camera, more noise than the newer ones, but still very, very nice.