Totally disagree on the only mobile point. I've been using Google Inbox as my main mail client for about 2 weeks now and it's great. Doesn't get sore on the eyes and my workflow with it is really quick (as in, it doesn't rely on touch to work). Yes I know it's a web app, but it may as well be a standalone application.
I do agree on not using material colours for app title bars. But that's my only real issue. I personally think material design looks great, and this example screenshot looks much cleaner and aesthetically pleasing already than the current linux offerings
Also, given that touchscreens on laptops and even desktops seem to be a thing now, this could well be a starting point for a Linux operating system which can scale seamlessly from smartphone to tablet to laptop. Obviously it's not for everyone, but it could be good as a kind of 'tablet plus', for watching videos, checking emails/facebook etc.
Although Sailfish OS and Ubuntu seem to be much more serious in that respect.
I personally love Inbox on my phone, but hate it on my laptop. I don't like how everything is so spaced out and personally don't find it easy on the eyes or matching my workflow at all. In fact, I've been trying to do as much of my email-related tasks as possible on my phone these past three weeks because of it, because Inbox itself is fantastic.
In terms of space usage, I' actually prefer the more spaced out approach. Other apps look a bit cramped and cluttered now in comparison.
A few related data points: I'm a developer and project manager.
I do all my work on a 13" laptop with nearly every app full-screen (I hate having two tasks visible unless I actually need both at once - which is very rare).
My eyesight isn't marvelous so that might be a factor. :-)
I do agree on not using material colours for app title bars. But that's my only real issue. I personally think material design looks great, and this example screenshot looks much cleaner and aesthetically pleasing already than the current linux offerings