"Quora has managed to assemble an incredibly high quality set of founders, VCs, angels, hackers as extremely active members of the community."
Anyone who has been around HN or Reddit for a while will tell you that the hard part is maintaining an intelligent level of dialogue, in the face of the massive crowd of mouth-breathers that come with open adoption. It remains to be seen what will happen to Quora's signal-to-noise ratio if it becomes popular. And if it doesn't become popular, the value is a huge question.
"Cofounders Adam D'Angelo and Charlie Cheever were former CTO/VP Engineering and Head of Connect/Platform at Facebook, respectively. They've managed to secure a massive investment at a huge valuation from a very highly-regarded VC firm - before launch."
This is practically a truism. In any case, it's not as informative a signal as it sounds -- people with successful pedigrees have an easier time raising money. It's hard to disambiguate this effect from the promise of the product itself.
" No one cares that you won't connect with Facebook or Twitter. Most people aren't like you."
Indeed. I am far more likely than the average person to try out a new service, if it's useful. Yet, with Quora, I am not compelled. I have no need for the service it provides.