Been using elasticsearch for a number of projects and all I can say is that it's really great! We almost replaced it on one large project to use it as a distributed storage but didn't work out cause it couldn't handle the load. (not surprising since that's not what it's exactly built for..)

However, as a search solution, elasticsearch is one of the best I've used this far (used solr, sphinx and fulltext search).

Hope this means that great things are to come! :)