Technically the thing is nothing new, the really important questions are those related to real life operation, and I don't see them answered.
* Position in regard to censorship, and technical tools to do, or counter it.
* Viability/resilience of the server which keeps comments.
* Under which jurisdiction it is hosted?
* If it depends on a domain name who owns it?
* Can a commenter be traced, and by whom?
* Can anybody (including original author) edit comments?