While I think it’s quite a good show, even excellent in a number of respects, my opinion is that unlike so many others Madoka Magica did not open the world to me. It is not the greatest magical girl anime I’ve ever seen, let alone the greatest anime, and rather than showing me that it’s possible for such a genre to be full of rich depth and interesting ideas it just reinforced my already existing beliefs in that regard. So, yes, an excellent show and a fascinating twist, but something I always knew was possible (in a good way).
I rejected Madoka for the nasty sight unseen, but I dipped my toes into, for instance, Uta~Kata, so I’m sympathetic to his argument. Also note Otou’s challenge in comments, about not enjoying “the dark perversions of the previously pure things you enjoyed” (Mary Gentle’s excrement on the topic of LOTR was the only book ever that I intentionally destroyed to make the world a better place).