Low dynamic range - Because you are looking at a standard RGB screen, you will only see light from a fairly low dynamic range of intensity. For example, if you look at the sun in the virtual world, it will not blind you. This seems like a petty issue but I think this lack of fidelity does put a huge damper on how real the image appears. Especially in a cockpit situation, you are usually sitting in a dark environment while looking on a very bright world outside of your windshield. The Rift dulls out this contrast and it ends up reminding you that you are actually just looking at a screen.