Surprisingly good. Stellar acting and direction. Sets, cinematography and costumes are beautiful, but not over the top. Their long hair isn't styled, but some is greasier than others. It has a very real feel to it.
And the writing is superb.
The fact that all the major plot points are straight from French history, gives extra gravitas to the overall production.
I was a bit disappointed that it's in English and not French, but that didn't bother me for long.