Limitations

Matching is yours. The library parses the query and combines your handlers. Wildcards, prefixes, stemming, ranking and fuzzy matching are up to the handlers.
Filtering only. A query does not sort, page or select fields: sort:date is a key like any other, with the handler you give it.
One syntax. The operators, keywords and date keywords are fixed, and in English.
No syntax errors to report. A malformed query is read as text, so there is no error position to show the user; see Malformed queries.
Size limits. Deeply nested queries, and queries whose OR groups expand too much, throw a QueryTooComplexException; see Queries from users.
Dates in UTC. Date keywords and relative dates use UTC days; there is no time zone option.
Database string handlers use Contains. For an exact match or another operator on a string column, register a custom expression.
No comparisons on enums in database queries. ExpressionQueryBuilder<T> only supports equality for enum properties.