One possible improvement could be a hybrid database solution, where parts of the application leverage a relational database alongside DocumentDB. If a system were heavily relational in nature, a database like PostgreSQL might be a good fit. 

However, it depends on the client's specific needs. We might use the document capabilities of DocumentDB for lookups. But, if the application is likely to evolve over time and benefits from full document database functionality, that would influence the choice. 

There's a bit of a learning curve at the beginning. However, once you learn the product, you understand it much better and it becomes easier to work with.

If you have many instances, many technical components in different regions, for example, one in France, one somewhere else, you don't need to build a YPO VPC. We call pre-work and you can connect with Amazon Document DB in the same instance. If you need to create in other ones, you need to build in the same thing or you need to build a replication of Document DB on it.

I'd like them to develop a graphical user interface where I can see how much of the solution I'm using. For example, so I can gauge which queries I need to optimize. 

The technical support could be improved.