[vhogemann]

If you're trying to use MongoDB as a relational database, and don't understand its limitations and strengths, of course it will be terrible.

MongoDB is good if:

a) Your data model fits into the document model. Usually that means you'll be querying only one collection at time.

b) The access pattern of your application is a lot of READs and few writes. MongoDB has a collection lock, so it sucks for concurrent read/write operations.

c) If you need ACID support, your operations must be restricted to a single document.

If your problem fits on the restrictions above, you probably won't run into many problems. We've been using Mongo to store our authentication info, and to store payment transactions. No major problems so far, but our needs fit nicely into what MongoDB can provide.

Most of the rants I see are from people that got burned trying to use MongoDB as a drop-in replacement for a relational database.