I worked with incredible people on fascinating problems. I was faced with interesting and novel problems every day and boredom was never an issue whatsoever. There were so many opportunities to break out of your specialty area. Backend engineer? Try working on the browser runtime for a few weeks. Frontend engineer? Why not work on system design for a few months. That's a rare find.
Minpunten
Leadership didn't make decisions in a timely or clear manner. Sometimes they would pit employees against each other in shocking, obvious ways, Elon Musk style. The good news is that everyone on my team was such a good person that nobody really fell for any of those tactics.