I love jadzia and didn't like her replacement as much but yes her death was rubbish.
Jadzia is probably my favorite female character in all of Trek. All her qualities that were already mentioned above made her a very likable and believable character.
I think she was the best female character on DS9. I know so many people really love Kira, but I just couldn't stand her. My friend told me I was being too harsh on her since she did have to live with the Cardassian occupation, but to me she always came off as whiny and annoying and I couldn't get past that.
That's why I love Jadzia and even though I knew she would die (a friend accidently spoiled it when we were talking about DS9 and I said I really liked Dax and he's like "which one?") but I think everything about her, except that BS death she got was fantastic.
Kira is amazing
she is one of if not the best thing about deep space nine.