Would you be able to sum up the things you consider Mongo to be extremely good at? Particularly in comparison to things like Riak (which I believe supports a si

Would you be able to sum up the things you consider Mongo to be extremely good at? Particularly in comparison to things like Riak (which I believe supports a similar data model), or indeed compared to an RDBMS. All databases perform poorly if you try to use them for use cases they don't fit, but I find with NoSQL databases it can be hard to find concise, objective statements of which use cases each is ideal for.