Newer cameras maybe more efficient or have larger battery capacity. They also have a GPS timeout setting that the D200 does not have and many found caused the camera to constantly remain on. GPS usage was not very popular when the D200 came out, but has become more standard for many shooters. The GPS units were also expensive and required an other Nikon accessory for attachment.
A lot depends upon how one uses the camera and what one attaches to the camera.
The camera, as all Nikon dSLRs, continually consumes battery power while the exposure metering system and focusing system is active. You can set the camera to timeout interval for these functions and the camera will enter a sleep mode. Half pressing the shutter release will wakeup up the camera.
Chimping every shot will also consume a lot of power. Use it carefully.
Tethering the camera to a computer will force the exposure and focusing systems to an on state and disable the timeout. Also the camera does not receive power from the computer.
VR lenses will consume more power than non-VR lenses and when turned on works whenever the shutter release is half pressed.
Attaching an active GPS to the D200 will force the metering and focusing systems to an on state, and there is no time out setting for this action like newer cameras. The only solution is to turn the camera off and on as you need to use it. The camera will start up fast but the GPS connection may take a while to engage.
I find the battery can last more than one day if one is careful and limits use of the GPS.