It wasn't meant to be. But in a way it is -- mongoid is so useful, that it's worth putting up with some of the flaws in its release/upgrade management. So, it's temperamental. Like owning a Jaguar.

It isn't.

We have used Mongo for good reasons, it's been appropriate for our workload, and we have used Mongoid since the inception of the product long before I joined the company. Replacing Mongoid at this stage would be a massive piece of work.

I find Mongoid's documentation is vague and lacks important detail, and the API itself violates the principal of least surprise frequently enough to be a problem.

It really is the ugly stepchild of ActiveRecord, in whose image it was created, and which by comparison has been a pleasure to both use and to manage.