What are the disadvantages of Material Design?

I'm generally a fan of Google's Material Design UX framework. Its positive aspects have been well-covered by the press and Google's own design group and evangelists.

But, the disadvantages of the system are much less documented, as a simple search shows. So the question is:

What are the disadvantages of Material Design?

I'm not looking for subjective opinions here (e.g. I don't like the color scheme), but rather for concrete drawbacks based on clear design logic or measurable observations.