Something has always felt a bit odd about Blender’s viewport rotation and I was never sure exactly why until recently when I did a comparison with another 3d package (Wings 3d). Blender seems to reverse the direction of rotation when you view a model from a different angle. For example if you view your model from the top and rotate, dragging left with your mouse, the view rotates clockwise around the Z axis. Looking from the bottom of the model doing the same thing the camera appears to rotate anti-clockwise.
I find this to be quite disorienting. Is there a way to change this behaviour so that the camera always rotates in the same direction?