Code, file structure, database design, the basics are very well done.

The code, the file structure and database design, the simplicity and power of the override system, the documentation at the api level. It is all high quality, well thought out, well laid out. These guys are masters at developing high quality code that as much as possible takes the complexity out of the user interface.

It is pretty cool how they laid up file structure to appear and act essentially as an operating system unto itself. Maximum flexibility, adaptability, scalability is the result.

Only thing missing is simple "git er done, don't bother me with details" instruction manual.