I'm with you on this! I've always expected her to die, but I don't want her to become mad or the bad guy. I've always thought and hoped that she would become more ruthless, but that was it.
Even if Dany didn't get the throne, I wasn't expecting Bran to become king and it was kind of a turn off, tbh. I've always hated the idea of Jon or even Sansa becoming king/queen, but even that would've been better than King Bran. That was very disappointing!
So, to me, there's nothing bittersweet about the ending. It's just bitter and it did made me a little bit less excited about the books. However, I'm still going to read them (if GRRM ever finishes them), because the characters' journey still is very interesting and enjoyable. Besides, the books will probably explain certain pre-ASOIAF events, like the things that led to Robert's Rebellion, which to me is also very interesting, maybe more than who gets the IT.