I've never used Ruby on the application layer, but I'd be wary of using an ODM with MongoDB. The single most shocking issue seems to be at the application / ODM

I've never used Ruby on the application layer, but I'd be wary of using an ODM with MongoDB. The single most shocking issue seems to be at the application / ODM level. Using the official 10gen-supported drivers gives you more control and a better understanding of what's going on every step of the way. Also, a thorough understanding of MongoDB indexing, advanced queries and schema design would have squashed all of these issues. Has anybody had a more pleasant experience with a MongoDB ODM?