Amen to that. The first time I used MongoDB it was stupid easy to get started. We implemented data replication from MySQL into MongoDB in a 3 hour hackathon, something that would have taken at least a week for a relational database. For a full description of the experience see:

http://scale-out-blog.blogspot.com/2011/05/introducing-mysql...

Don't put down 'easy'. It's incredibly hard to do well.

P.s., I'm DBMS guy and have lived and breathed Jim Grey-style transactional consistency for decades. I'm still impressed by what they did.