> It's very portable it scales well and it is fast

How about some numbers to back you up?

I think the authors main gripe with MongoDB was the lack of ACID transactions

That's largely accurate, but the core point that I try to convey is that Mongo's key sales pitch is that you get sharding and scalability, but at the cost of features like ACID transactions, foreign keys, consistency checks, etc. Today, we have a great number of options that don't have to make these pyrrhic trade offs, and are just as scalable as Mongo.

If you want something that's portable, pretty scalable, and fast, go with Postgres. If you need something that's really scalable, there are plenty of other good databases on that list.

That's a poor argument and the comparison is just unfair. Actually, I am disappointed the author mentions Auroa but not Amazon DynamoDB. Half of the contenters are RDMS so it is totally unfair to suggest move off / move away from MongoDB because it lacks ACID. Furthermore the article really lacks technical comparison in depth. This is more of a notebook. Don't get me wrong I have used Mongo and I know it some of the common problems beginngers will find. As with every database there are gotchas. Postgres out of the box is great but doesn't mean it is the right fit for every problem and you still should fine tune your database.

DynamoDB is just not good. It has a document size limit, and throttling. It gets very expensive very quickly. And it's not fast. Writes are slow. And it's difficult to query.

Yes DynamoDB is indeed quite expensive - and increasingly so as data size and traffic grows. The whole point of distributed datastore like Dynomodb is to scale out massively by compromising on many database features and flexibility, but what's the point if it becomes so expensive at large scale?