Would be curious to hear what Elasticsearch is doing wrong if you don't mind. I have no dog in the fight, I just always hear good things.
Trying out Elasticsearch, my experience was that it really wants to be run in a cluster, but it also loses data pretty easily. I had more issues with it crashing and it's generally a lot hungrier for memory.
Both have non-obvious shortcomings. Solr's schema will make you believe that it likes deeply nested JSON documents. False! It actually wants pretty flat "documents" without nesting (you /can/ nest, but it usually doesn't do what you want without some extra legwork). ES will have you believe that it supports lots of query types and they'll all perform great on semi-structured data. My experience was that it was difficult to predict performance, but that generally the fancier the query the worse it would be.
Solr's querying functionality is not extremely powerful (though they "helpfully" made it offensively complex with different query parsers and stuff) but performance has always been excellent for me.
IMO, if you don't need clustering, Solr is definitely better. A cranky but robust piece of engineering from before scaling was everything. ES has better documentation, a better "getting started" story, and is generally a lot more user-friendly. Aphyr's posts about it have made me wary of using it without a re-indexing story.
I haven't tried Solr's scaling stuff because I haven't needed it, but I would expect it to be in pretty rough shape compared to ES because it's not a primary use case for Solr and it is for ES.
The new SQL / Parallel Streaming has also made querying multiple collections a cinch.
Most of the problems that I have had are with the ZK clients and not the server. As long as you follow the operational documentation (there are a few basic rules) it hums along nicely. We have a few clusters with Kafka and have a decent process in Chef:
On the other hand, it's had its share of improperly handled split brain scenarios. I still think it has problems with partial split brain (where A and B can't talk, but C can talk to both of them).
Zookeeper as a hard requirement feels like asking me to supply an entire container port to unload one container from a semi-trailer.
Thanks for sharing the cookbook :) . Do you use Zookeeper for anything other than Kafka?
I just clustered ES with Docker somewhat recently. It was pretty good at discovery I must say. Well, I'm no great search engineer I just throw these things up when I need 'em so good to know all this. Thanks again.
When you spend lots of time fine-tuning the exact combination of filters, ranking algorithms, weighting of fields and so on, the api just completely switching certain methods kind of hurts.