The only downside we've hit with ES is poor documentation. In all other respects, if you need search, I can unconditionally recommend it.
Did I mention it is awesome?
If you haven't had a chance to play around with ES - you really should. I've never used Lucene or Solr but I picked up the basics of ES really quickly. You can roll out some really impressive search capabilities with embarrassingly little code (or knowledge).
Just this last weekend I migrated servers and syncing my new server was as easy as installing ES, joining the cluster and letting everything transfer over automatically. ElasticSearch comes as close to "magic" as possible, especially for something as sophisticated as search.
Congrats to all involved.
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! :)
I hope this announcement doesn't change anything (at least not too much!).
6 months ago when we started using it, we'd have easily hired you guys to help us out with our use cases/jvm optimization.