I enjoyed the fight, even if we didn't take out Siren herself. It was deceptively difficult the first time I went through the quest since I didn't take out the magic wielding skeletons who chipped away at quite a large chunk of my character's health. I'm glad we didn't kill Siren there, though - it leaves room for her to show up again in the future as a Primal battle of the same vein as Ifrit, Titan and Garuda.