No major problems. Lots of comments, but somewhat overeager text substitution to save space. Sparse high-level documentation considering the complexity of the system. Complex OO framework, automatic persistence. One player dropping link caused the MUD to segfault.
All functions have comments.
There's lots of player documentation as well as a verbose description of design decisions and considerations available. Several compressed external data files. No problems observed. Implements a interesting though bare-bones event system. No rooms, objects.