I love American Horror Story. Here are some flaws that I personally see with the series. The flaw that stands out most to me is repitition. Last season, a killer (Tate) raped a woman who concieved a physco child. This season, a killer (Thredson) raped a woman who concieved a physo child. This season's dwelled a lot on pregnancy and babies, which was a main concept of the last one. There are some more similarities too. Ryan Murphy needs to focus a bit less on pregnancy and babies post-Asylum. All in all, American Horror Story is an awesome series that I have been with since the start.
Other ways to view the repetition is variations on a theme or as the creator's trademarks/tropes. Pepper is likely a variation on Murphy's use of actor's with Down's Syndrome. Baby drama has occurred in every one of his shows. Look at these things as easter eggs rather than a lack of new ideas and you'll increase your enjoyment.
I love that there is no sooky soft love stuff, I love how original it is even though there is some repitition or lifted bits, it still works really well and forms a gripping serial. The 'flaws' fit and I cannot wait for AHS 3, wouldn't even bother me if there were to be more psychos and babies to come