I haven't seen this new design, but one thing I noticed with the flat design trend is that too many strong colors are used, and this causes fatigue in the long

I haven't seen this new design, but one thing I noticed with the flat design trend is that too many strong colors are used, and this causes fatigue in the long run; for example I noticed this in the latest updates to gmail on android. But I also guess that with a flat design it is inevitable to resort more to color to differentiate your design elements.