&#62; documentation is spotty<p>True, but we're working on that (and we're very responsive on IRC and mailing lists).<p>&#62; not enough big projects are using it<p>I don't think that's true anymore; Digg, Facebook, Rackspace, Twitter, Mahalo, Ooyala, SimpleGeo, WebEx, and others are using Cassandra: <a href="http://n2.nabble.com/Cassandra-users-survey-td4040068.html" rel="nofollow">http://n2.nabble.com/Cassandra-users-survey-td4040068.html</a>