A paper comparing MySQL and Neo4j coming from the Dept. of Computer and Information Science of University of Mississippi:
The evaluation methodology designed to compare MySQL and Neo4j involves objective benchmarks and subjective com- parisons based on system documentation and experience. The objective tests include processing speed based on a pre- defined set of queries, disk space requirements, and scalabil- ity. Subjective tests include maturity/level of support, ease of programming, flexibility, and security.
I’ve seen a MySQL and Neo4j benchmark before.
Original title and link: A Comparison of a Graph Database and a Relational Database (NoSQL databases © myNoSQL)