Disclaimer: I haven't read it.
It sounds like you're asking some good questions about evaluating a new framework.
While maintainability and community assistance are key, there are some other things to consider.
How far along is your application? Is it profitable (not just monetarily) to add more framework? What is the framework providing you?
Are there any downsides to the framework (speed of his "cell" views on page render, for example)?
What are your other options? Service Objects? Classic Ruby Architecture? Model-Views? Presenters?
While I'm not personally a framework kind of guy, I do like seeing new approaches. This looks a lot like the Zend PHP framework, but I may be totally wrong.