I use it for two major reasons:

1. It's distributed. I can elastically add/remove nodes. I need this not so much for scalability, as for reliability, and I want to be future-proof.

2. Changefeeds. Nothing else even comes close, and my entire application is built around them.

I have no show-stoppers. The thing works. Sure, I'd love to see some things done differently (ReQL looks nice at a first glance, but has many limitations in practice, causing code that ends up being quite complex), but overall even if it were to stay exactly the way it is now, I'd continue using it.