I can understand why some movie critics gave poor or average reviews to this movie when it came out--it's indulgent, true...but that spirit matches the subject matter so well: I think it's genius!
Of course the costumes and the settings are amazingly perfect--heck, you could watch this movie on mute and enjoy it immensely. The music, score, and casting is also perfect--Jason Schwartzman as the King is a revelation--he's stuffy, awkward, and totally hilarious.
The only reason I didn't give it 5 stars is because I don't love Dunst here. She's great towards the end, when things start to unravel--she wears the weight and sadness well. But earlier in the film, she's a bit goofy, self-conscious, and even overacting at times.
I love how the movie just gives you a feel of her life. Sometimes these historical movies try to represent an age with a kind of "antiquing" to it--the way we see it now. But this story is presented in full color, the way THEY lived it! I think it would be appropriate to even show clips of this movie to history classes, just to give a feel for the age--especially the scene of Marie's complicated morning routine with all the ladies of the court...