I rarely initialize my use of Quora by visiting the website - I have found immense value in the digest emails they send. They are a mix of things they know I'm explicitly interested in, and generally "interesting" things (presumably defined by popularity). Probably 90% of the time after receive a digest email, I open at least 2 or 3 of the links within.
I have tried visiting the site directly and am rarely able to find content as stimulating as the links they send in the digest emails.