The N1QL language and features have been improved in Couchbase 5.5, with enhancements including ANSI join improvements, index partitioning, and grouping and aggregate performance boosts. The new version also includes security features such as auditing and x.509 support, which make it easier to meet compliance requirements. Couchbase 5.5 improves query and indexing performance, making it a significant update for users of the N1QL language.