Cassandra is a Key-Value store using column families. That's not the same as a columnar database. They're almost complete opposites, in fact.
>One of the reasons the community was said to have taken so long over the release was the desire to improve quality.
The actual reason is the ASF and Datastax had a big ol' falling out and Datastax took their ball and went home. When the rest of the community didn't follow they sheepishly came back to the fold last year.