Temperature - This is meant to store ambient temperature. While this is potentially informative, cameras typically do not measure ambient temperature very well because they are usually warmer than their environment because they are being held by warm hands. A sensor temperature measurement would be much more useful because this may be used to select the dark frame for noise removal from astronomical images.
Humidity - I applaud the idea, but I've never seen a camera that measures this. This could potentially be very useful for FLIR cameras (forward-looking infra red) because they need this measurement for an accurate calculate of atmospheric attenuation in determining the blackbody temperature of the subject.
Pressure - Air pressure in units of hPa. Good idea.
WaterDepth - Water depth in metres. Negative is above water level. Nice.
Acceleration - Directionless acceleration in units of mGal (10^-5 m/s/s). This is of limited usefulness. Why not include a proper 6-axis acceleration?
CameraElevationAngle - Nice, by why only one angle. What not a 3-axis Pitch, Roll and Yaw? These angles are very useful for many applications, yet still missing from Exif.
I guess I should be happy that Exif is not dead, and that JEITA is at least continuing to expand the specification, but it would be nice if they listened to the metadata community and not just the camera manufacturers when developing the standard.