One of the aspects of Myst that made it so enthralling was the beautiful, pre-rendered landscapes with complex lighting, high-res textures and high poly-count models. Real Myst had to sacrifice a lot of this to render the world in real-time on the average PC back in 2000.
If the graphics could be scaled up to push the limits of modern hardware then it could match the beauty of the original and this would earn 5 stars, but I feel that free-roaming and mouselook weren't worth the graphical sacrifice.
Overall I feel that the original is the superior version to fully experience the facinating worlds of Myst, although the 'bonus' extra world might make this worth playing if you've enjoyed the original.