The integration to the shell is nice but the implementation kind of sucks.
It seriously needs to be tweakable. With a GUI, not scripting.
For example, message pop is far too short. I can't notice the pop and refocus to read it before it vanishes. The text is also much too small. And, being Gnome, there isn't a single option anywhere that would fix it. It also only pops on one monitor, which I might not even have in my field of view.