I'm currently migrating from HBase to Riak.. and I'll just say that it is a huge breath of fresh air, compared to dealing with HBase. I also played with MongoDB

I'm currently migrating from HBase to Riak.. and I'll just say that it is a huge breath of fresh air, compared to dealing with HBase. I also played with MongoDB for a bit, prior to Riak, and found it to be incredibly fast -- but Riak's ease of scalability was a huge win for me.