None, in fact. But reading round, it was clear that Madoka is different, so I tried it.
For one thing, here is an anime with an all-girl cast, but with
no fan-service - nope, none at all. Even less than Azumanga Daioh, which has a little, but inoffensive and appropriately linked to the action in any case.
Then the art - it is fantastic, most notably the fantastical realms of the witches themselves; but the whole thing is beautifully done. I presume that the more cutesy aspects of the art follow the norm for magical girl stories - but they are well done in any case.
Then there's the story. Not so much "magic fixes everything in the end" here. In fact it's pretty dark, especially when
we discover that the magical girls are in fact the source of the witches they think they are defeating.
And then the ending - Madoka makes a wish which seems to get round the limitations, but
then we are shown that although there will be no more witches, there are still other evil beings to be fought; and it's not clear that her decision, though it does what it says on the tin, is really a significant improvement for the future.
Of course, nothing can be immune from criticism, and here I would point at the slightly flat personalities of the characters - especially Madoka herself, who shows less development than one might like to see. Essentially everything happens around her, until the point is reached that she can step forward and make her big decision which changes everything.