How does this compare to graph databases like neo4j? Would anyone recommend using this for working with actual graph data structures?

If you want graph algorithms -- not yet. If you want ability to easily work with hierarchical data to build apps--it's the best.

Hey, I have started using the course yesterday, opened just now and my statistics are gone... Is there a way to report a bug?

Checkout calibre for converting to othe formats: https://calibre-ebook.com/