I would only suggest not watching Hidan no Aria if you absolutely can't stand characters with loli/high-pitched/kinda-whiny/tsundere builds, like Shana(Shakugan no shana), Nagi(Hayate no Gotoku), Taiga(Toradora!), Louise(Zero no Tsukaima). But don't get me wrong. That description of Aria was the quickest way for me to describe some qualities other people may find undesirable. To me, that description sounds way exaggerated. I loved Hidan no Aria, and you should definitely go watch it