ES has performed very well for us as the backbone for the solution we deployed for a large government-sector customer. Had some GC issues initially, and were worried about user concurrency, especially since we were not restricting queries (i.e. users can do full-scale wildcard searches against the entire data set of 1BN+ records). But ES continues to shine.

Congrats to the ElasticSearch team, and all the supporters around it. Once I get back into more of a coding role, I'll definitely be contributing back to the ES project.