[yehosef]

This is one of the undersung benefits of ES in my eyes. Relevancy results requires tuning of the indices and queries and in most cases (that non IR-experts would program) ES will give as good results and be as easy or easier to implement as Solr.

But after you've gotten over that, you realize that this new tool can do lots more things than just text search. Time series metrics, BI, predictive ML, APM, etc. with relatively little work. With Solr, you could do those non-IR tasks, but it's going to feel much more awkward, IMO.