I have been a long time user of Quora, as well as a long time detractor.
While I think there is a very interesting critical mass of user, I agree that it is largely a valley audience. There are some really interesting answers on there, which I have found valuable; but I have maintained that its flaws are too big and too many for my tastes:
* The UX sucks. While they have made some minor improvements - it still sucks. I had posted about this prior on Quora as well. It was also made worse by their constant self-back-patting on the UX/UI where they were claiming that the users were too stupid to understand the design decisions they made, and that they were in fact design decisions not mistakes. They were constantly praising how they learned so much about good UX from facebook.
* The lack of threading is retarded, and makes discussion impossible. The fact that you can only have 1 sub level (a comment) is just wrong. The claim was they didnt want discussion and that the answers to the questions were meant to be definitive thus not needing discussion. BS.
* The colors and fonts/sizing used is horrid and makes it very difficult to navigate. The use of 'facebook blue' the light grey and then the bold black are all in the wrong order. (http://i.imgur.com/Y9EPV.png) It doesnt work for quick visual scanning.
* The entry boxes are broken; when you begin to type something, it hijacks your cursor and disabled the backspace. e.g. if you try to type @username or http - it makes it difficult to fix typos.
* it is impossible to navigate topics clearly, sort or save any meaningful data. You cannot tag or vote in a meaningful way so as to promote answers either. You can only browse a subscription/follow feed in a linear 1-dimensional manner.
Ultimately, Quora is a one dimensional service which had a lot of early hype due to its founders and early adopters having real influence in the valley.
There is good info, but the architecture of the sites containment of that data is like the work of a talented child with a lot of potential being praised for their genius too early and resulting in stagnation and reinforcement of an idea that started as a good seed, but was ultimately not thought out well enough to scale - ultimately feeling dated and as more-broken-than-not implementation.
So, I go there about once a week for a quick scan - or travel over via HN links to good posts, but I spend very little time on there any longer. The information value in exchange for my time there is too low any more.