I don't understand all the negative reactions. Canonical is recognizing various problems in making GNU/Linux mainstream. They are then innovating at a deeper level (fixing root causes rather than duct-taping) to ultimately attempt to really attract the layman to a mobile or desktop GNU/Linux distro. Devs don't need to target Mir if they don't want to, Linux users can switch to another Debian if they don't like it, an…
Furthermore it is horrible because Canonical has a history of secrecy and authoritarianism and they absolutely go against the spirit of open source software development.