MongoDB 3.4 was recently released with several significant updates, including support for graph processing, multi-language collations, read-only views, faceted navigation, new aggregation operators, performance improvements, and more. To evaluate MongoDB 3.4 against an existing production workload running in MongoDB Atlas, users can spin up a test environment from a backup, upgrade the test environment to MongoDB 3.4, execute their test suite, and if all goes well, upgrade their production cluster to MongoDB 3.4. This process involves creating a new MongoDB Atlas cluster, restoring a backup from the production cluster into the test cluster, upgrading the test cluster to MongoDB 3.4, executing test suites, and finally upgrading the production cluster if tests pass, all while minimizing downtime and ensuring application availability.