Hey,
I think the mouse orientation in the 3d view is 90% right, except way the mouse rotates around the y-Axis (pulling the mouse left/right). This isn't really intuitive and actually quite confusing. The camera rotates around the camera up vector, but should rotate around the world up (or global y-Axis) vector.
Either way, there should be an option to let the viewer decide if he/she wants to rotate around the view dependent camera up vector or the world coordinate system up vector (or Y-Axis).