He posted on twitter:
"I suppose I will get a FB account now, so that may lead to some writing a little longer than tweet length..."
Never signing up for FB account indicates to me that he's got as much disdain for Facebook as many people here.
He also tweeted:
"I have a deep respect for the technical scale that FB operates at. The cyberspace we want for VR will be at this scale."
Which hints to me that he's at least intrigued by the possibilities that partnering with Facebook will offer, and he sees some potential in this partnership.
Carmack has earned enough of my respect over the last few decades that if it turns out he's ok with the acquisition and stays with the company, then as much as I dislike Facebook, I'm going to trust his judgement and be confident that he's hard at work on something 'game-changing'.