The big theme: Google got big, and was no longer so much fun. That happens to all successful startups. Google's culture isn't immune.
Someone calls it "Culture leak". Same thing that happens to social networks or forums when they get big.
BTW, the quote Philipp highlighted mentions the infamous shipping containers (which I posted about long ago, and people tended to doubt the veracity...)
One of the ideas he championed was to build portable data centers in cargo containers, a project Google tested in its headquarters parking lot. But managers were too timid to pack in enough servers, so the experiment was not cost-effective and was ultimately canceled, he said.