I don't think the amount of controversy Facebook is receiving on this is justified. The patent license could maybe be adjusted, but people's interpretation on this seems to be geared towards spreading FUD over facts.
The provided licence is a discriminatory licence that favours only one party - Facebook. I believe that it could not be called an open licence.
Author argues that the situation is not that bad and it is still somehow an open licence or even when not then it is still acceptable. I believe that it is neither of them.
They have been asked by the community to modify the PATENTS grant approximately 3 times in the past 5 years. They have flatly refused every time.