See: http://mongoalchemy.org/

This project is almost entirely driven by what people need. There are still quite a few things which MA can't do that the standard mongo driver can, but they are largely things which I don't need to do (in particular, I basically never do server-side code execution for performance reasons) and so I don't have as good of a grasp of what the common use-cases are or how to best make them easier to deal with. If MongoAlchemy doesn't do something you need it to, please file a bug/feature request. I try to be very responsive.