To me, the benefits of MongoDB have always been that it makes the two biggest challengers developers are faced with when creating an application easy: Building and Scaling.
Being able to efficiently build and scale an app only makes the end product better.
I remember nearly shitting my pants when I heard the rumor of Marklar's existence. Yeah it makes sense now but it was amazing that it actually existed at the time.
This engineer did an amazing job of porting the laptop version over considering it probably needed power management and most likely support for Sony's proprietary garbage. That is something even linux has trouble with nowadays!
I did a lot of the same things as Mattan, some of them sitting right next to him, in order to get up to speed on Rails enough to build a web app. It was not easy. I had about 6 weeks to learn Ruby, Rails, MongoDB, and mongoid to build a web scale app and I can definitely say that the advice he gives is invaluable.
Do every single tutorial you can find. Eventually the information sinks in.
Congratulations Mattan. You worked hard while so many founders out there just hire people to build their dreams for them. You are an example of what is right in this industry, true entrepreneurialism.