Ubuntu (or should i say Canonical) is now under criticism from many developers after they tried to create another project which is called mir and also other things that iritated the Open Source developers. It seems like they wanted to create their own world without considering what others have been doing and instead of contributing to that project instead, they wanted to make something that is based on their own assumptions. It's more like what Microsoft had been doing in the past. They created their own spesifications, standards, and forced others to follow them.
Somehow, they failed to realize that Ubuntu is failing since few last releases. Their user base has dropped since then and many of them migrated to LinuxMint. I think they need to think about that issue instead of creating another project which will confuse most of their users in the future.
I must say that the spirit of Ubuntu is fading on each release and if they don't do anything right on 13.04, more users will leave Ubuntu in the future. I can guarantee that.