After the recent loss of an aeroplane due to incapacitated crew, I thought this was an interesting example of how hypoxia affects pilots (well, or anyone else really) from 2006. Fortunately the ATC realised what was going on and ordered him to descend.
More detail at http://www.zerosixright.com/pilot-suffers-extreme-hypoxia/LiveLeak
Remarkably, the captains inability to turn on autopilot requires him to have to work in order to fly the airplane, keeping him conscious and the plane airborne.
The pilots words gradually become more understandable, and around 11,000 feet, he returns to normal and confirms that he had, indeed, been suffering from hypoxia. NOT from today's crash.