Not convinced but should put my hand up to say that I've not come across a single instance where I've needed it. Think going forward the point at which people and organisations transition to NOSQL will become larger and larger because problem cases will be increasingly solved as we transition to better hardware and improved bandwidth.

On point 5 of David's post I would argue that you can set up relational databases to have a key value format - I kind of like that format for somewhat random child records where parents can have very variable number and type of child records and my investigation of that format was brought about by trying to understand what everyone was talking about with NOSQL.

It is a very good point that the relationships in the data is as important as the data. A point that people starting out don't always get.