Neo4j 3.4 offers significant improvements across various aspects, including scalability and performance enhancements, new features for the Cypher query language such as spatial querying support and date/time types, Multi-Clustering support for horizontally partitioning graphs by domain, improved read performance with a new runtime that improves performance by roughly 70%, faster write performance due to native indexes optimized for graphs, rolling upgrades for operations and administration, enhanced spatial and date/time data capabilities including geospatial graph queries, and a new security feature focusing on property-level security.