I also have tried to do some tests with it, but I haven't got past getting an error saying that it requires the Twig library.
The bottom line is that the current documentation assumes too much information is already known by users, also, I also wonder whether it needs to work within Symfony or not.
I a really interested in this library, it has really useful and necessary components, but the documentation is insufficient to get you in, it would be nice to have an existing simple test project with plenty of information on what is to be installed and a walk through. This would make a lot of people interested.
Also, it is not clear what the class generation really means: is it necessary? Once I need to modify a schema do I have to generate it again? And finally, how can I work schela-less, since that is one of the nice things of Mongo...