I've used MongoDB quite a bit, and find it convenient. That said, it also has flaws (many has been pointed out on HN and elsewhere). It's schemaless and mallea

I've used MongoDB quite a bit, and find it convenient. That said, it also has flaws (many has been pointed out on HN and elsewhere). It's schemaless and malleable, easy to restructure the data. Fairly easy to operate, replication is easy to setup. Don't use GridFS though, I'd go for S3 or similar instead.