They were quite open with feedback which is another reason I have good feelings towards the company. The whole process was very quick - responses in days. Compared to what my friends tell me about Google's sometimes multi-year process, it's a dream.
I don't know how much I can say about their internal structure but what I found very cool (especially as a former Rocket Internet employee) was their focus on and methods for detecting and spreading knowledge across the entire organisation, which is sort of decentralised even if many important decisions are made in California.
This is something we never got right at Rocket, where companies and regions are much more independent and have wildly differing methods and standards. It was very rare for things to cross over beyond the "startup code" (the PHP e-commerce codebase that is sent over to be deployed when a venture is opened) and some marketing methodology. The other large companies I've been familiar with are better at sharing information, but tend to have a global hub where most of the thinking is done anyway (i.e. knowledge tends to radiate outwards).