The problem with humanity is that we take things that work for granted, and when something doesn't work it stands out, and we like to complain about it. In a way it's not that bad, since the best way to improve oneself is to fix what is wrong more so than concentrating on what is right.
But that said, I was there for only one day, unfortunately, and I thought they did an excellent job. Plumbers concentrates on developers (both kernel and userspace), and they do a good job at keeping that focused. Plumbers is still very new, and there's lots of places that they can improve on. But what they have accomplished so far, is worthy of compliments. Kudos to Plumbers and those that worked it.