interesting development but not so good.
Keeping old code (gtk2) alive when their is a way better gtk3 version is just being plain ignorant. They should fork the latest gnome version, drop the default gui and develop and upgrade the fallback mode. In the end that will also benefit Gnome. Note that this isn't the first time a "fork" is attempted. A couple years ago their where a bunch of patches that gnome wouldn't accept. Those where all put on a site and where kept up to date for some time. It never came to a full fork and it eventually died.
as for "dash" .. That's both smart and stupid of canonical. Smart, the use of QML since that way they both have software and hardware rendering depending on the used hardware. That's very smart! However, they are using a Gnome environment with Gnome apps but with this they add a huge Qt dependency.. That is not so smart. But hey, they can't rely on cairo for this stuff
Yeah, two interesting developments but both aren't that good in their current form.