Notable advantages include:
1. Modules can be written in any language as long as they follow the protocol listed here.
2. A significant amount of calculation by one module will not hamper the execution of other modules. In other words, one module can't cause an IRC timeout.
3. A bug in a module will kill only the module and not the entire bot.
4. It's really easy to expand to handle IMs and any other input format you'd care to handle.
5. Any module can be killed and reloaded at will which makes tinkering quite simple.
Here's the user manual.
Here's the operator's manual.
Here's how to write modules.
Here's the code archive.