I enjoyed both DAO and DA2 thoroughly, and for the most part found no problems with the flirting between npc's and my character, regardless of gender (I found most of what Zhevran said to be hilarious).
My only complaint regarding this sexuality issue was how Anders' character was retconned if you are a male character in DA2. In Awakening, he seems to fly pretty straight (settling down with a lady being one of his aspirations at some point if I remember correctly) and this persona carries through if you choose to play a female Hawke. On the other hand, if you are male, they incorporate a homosexual relationship with a fellow circle mage into his backstory.
I found that this Anders was as equally believable as a character, and I understand that Bioware was responding to people's concerns that Alistair or Morrigan refused same sex romances, but I feel that a character is stronger if the developer can decide on what he/she is. Characters that are sexually ambiguous (Zhevran) work well because that is the way they are. Creating a character who hasn't chosen sides yet (Leliana) also makes sense. An openly gay (and only gay) character would also be an impressive decision for Bioware to make. But going back and directly altering a character's backstory goes against creating strong characters (in my opinion). Why cant my male Hawke get props from Anders about the women I sleep with, stuff like that. If Bioware wanted Anders to be straight or gay depending on the player's preference, then why couldn't he be straight if I was a male?