Why are the above images samples of good 3D? Well for several reasons. Firstly, they have great depth and there is obvious distance between the foreground and background. There is a good separation between the stereo pairs. All objects have a nice sense of space between them and sit correctly in relation to the stereo window. All objects have a look of solidity and you feel as though you could walk into the scene. Also, the 3D scene is comfortable to view and doesn't suffer from blurriness. For me, these are the fundamental elements of good 3D and I would like to see a consistency of this type of 3D in all future 3D movies and other 3D production.
Please note: these samples are used for illustrative purposes only and no infringement of copyright is intended.