In the past I used to but have since moved on the ElasticSearch.

I found the scaling not to be as easy as they led to believe. I also constantly bounced against the 10mb limit of the aggregation framework.

My biggest gripe, however, was data storage. It uses way more data then it should and it doesn't free up disk space if you delete data. For my use case (web analytics) it was a dud.

Supposedly TokuMX fixes many of the problems but I had already migrated to ES when I found out about it.