I've been reading Evo for over a decade, and respect their work. I can tell you Evo doesn't give 5 stars lightly - even most supercars/hypercars have 4-4.5 starts. If my memory serves me, the F90 CS is the first M5 to earn 5 stars since...well, since my favorite M5, the E39.
Coming on the heels of the M2 CS (and after the somewhat disappointing F8X CS), it does seem that there is a subset of M engineers who are pushing the envelope. And for that, I am glad. Not glad enough to trade my M2C for an M2CS for my boring daily commute (and the unrealistic hope that I will be able to find time to take epic drives soon) or consolidate my dream 3 car garage (which, while modest, I have) into the F90 CS...but still glad that the R&D is occurring and will likely flavor M cars in the future.