Dart is a very refreshing change for front-end development. No fatigue! Great tooling, nice language without surprises and optional static typing.
On the backend you get probably the fastests dynamic language out there, maybe competing only with LuaGIT.
The new Flutter for high performance mobile app development looks seriously awesome. I specially love the instant live reloading.
Dart's package ecosystem (pub.dartlang.org) seems healthy with constant updates and new packages.
I have no idea how TIOBE works, but I find weird that people accuse Google of manipulating it to promote Dart. I believe it's the opposite, Google has done very little to promote Dart, and that's why you don't hear about it very often. I believe the project deserves more promotion because it's seriously good. Give it a try one of these days!
EDIT: I do not work for Google