Elasticsearch can index documents dynamically, and doesn't require a schema to create an index. Dynamic data types for fields may not always produce what you want, but it's possible to define a partial schema for the fields that are important and let Elasticsearch handle the rest.
The query language is verbose but I would hesitate to call it a nightmare. You can always search using the Lucene query language, and SQL support is landing sometime soon.
My last project required fulltext search and I was going to go with Elasticsearch but being dependency-averse (also complicates the deployment story), I ended up using Postgres' built-in fulltext search capabilities and it actually works really nice, especially after I added a little DSL to take advantage of the full power of `to_tsquery` (so I could avoid the oversimplified `plainto_tsquery`)
The query language is verbose but I would hesitate to call it a nightmare. You can always search using the Lucene query language, and SQL support is landing sometime soon.