What's with all the hate? That fight showed exactly what most of us already knew. Let's not act like Overeem was exposed, or Bigfoot had some miraculous turnaround in his career.
Overeem is a big, powerful kickboxer with superlative striking ability and good well-roundedness, but questionable cardio. He also has lapses in his fight IQ.
Bigfoot is a big heavyweight with a black belt in BJJ, knockout power, and great toughness.
It's no surprise that Overeem was pretty much coasting against Antonio Silva for rounds 1 and 2. When he's fresh, he's simply a stronger, faster, and more technical fighter. However, when round 3 happened, when he got a little tired and was not respecting Antonio Silva, Bigfoot hit him with big shots and finished him.
Alistair Overeem's skills and physical ability make him champion-calibur, but because of some of the weaknesses that he has, he'll never be able to have the type of run that GSP or Anderson or any of the other greats have enjoyed.