When I step back from the nitty gritty of the apps and look at the Material design documentation I can't fault anything in particular. However, based on my experience of the implementation I find myself doubting the usability of the apps Google has switched over to Material design. The floating action button is one of my favorite pieces. It encourages app developers to give their users just one main action on each screen. However, if you're suppose to focus on a single action, how do you work with complex systems?
Though Material design spends a lot of time thinking and talking about the how of these apps (how to use color, how to animate, how to layout the page), there's a big hole where the "why" should be. Why do things work this way? What are the logical connections here? What's here to inform the user? In these documents, the "why" is lacking.
As a designer, I can get bored with the tried and true approach. However before I get too excited and re-invent the wheel, I must clearly outline the why. Why do I want to change this? Just for fun? Is there a practical reason for doing this? Is it going to improve the user's interaction with this app?
Google has spent a lot of time explaining the design side, but not so much on the UX side. This results in some nice looking apps that don't work as well as they could. UX has always been part of design, it's just a question of wether the UX is intentional or not. Executing thoughtful UX is what elevates design from the cosmetic to the impactful.
So here's my big thought, Material design is a sophisticated design system that actually makes it harder to create apps with solid user experience. It is a system that makes bold decisions, but that requires a professional to do right. Since Google Maps got it's Material design make-over, they have released updates that address my transportation switching issue but not the close button. It is definitely doable, but it does take a lot of thinking, testing and time.
Aiming for the perfect blend of UX and Material design is a challenge I look forward to. The next chance I get, I'll make sure to start with the why and go from there.