I just found out that there is a Bioinformatics topic in Quora with a good bunch of interesting questions/answers, (I guess many people will already know about this but I didn't so far).
Personally, Quora strikes me as having vast "time-sink" potential, with little reward. However, I know people who find it useful.
The nature of the web is that sites with similar aims will continue to appear. You can view them as either complementary or competitive. Ultimately, whether they live or die depends on many factors: uptake, community size, funding models, maintenance.
I think that BioStar has a very strong expert community: people who really do bioinformatics, of all types, every day. And again personally, I no longer have the time to create accounts, explore and contribute at every web site under the sun, so I stick with the one that I think works best.
What is most important to recognize that each of these sites are only as useful the content stored in them, and that is created by the people that visit and contribute to it.
In the current BioStar I love the very low barrier of entry for contributing, the lack of advertisements and a fundamental focus on science and getting things done, rather than creating it as commercial vehicle that allows a third party to live off of.
I think these are the qualities that have made BioStar successful and will make it succesfull in the future as well. Of course this is not to say that we should not think of evolving and addressing needs as they occur.
Well, I tried Quora and I do like it. But for Bioinformatics questions BioStar simply is more into the real community. We could learn from quora as far as the organization of questions goes though.
For this kind of questions I never know whether a comment is really an answer, or an answer is really a comment...
I couldn't try Quora since it requires an invitation and I haven't received one so far. The invitation-based system might limit unintended use, it makes access not easy. I prefer biostar so far
I need to update this answer. Is says that you need an invitation when you try to login at the main page. If you however follow the link above, you get access. Still I find quora less transparent then biostar. With Biostar it was "love at first sight". My first impression on quora is so so.
Don't know why, but I tried Quora and I really didn't like it. BTW, this question should probably be community-wikified.
I agree; any "meta" question should go to community wiki straight away. Doing that now.