MongoDB is awful for development.

I once started consulting on a Rails app project which used MongoDB. But I was never able to get productive: I had my development environment all set up, but then the code wouldn't work with the development database. I pinged the other dev:

"Oh, I made changes to the data model. I'll zip up and email you a new copy of the dev database."

This continued for a couple of iterations and I had to quit the project because I could never continuously get work done.