I did see Estinien getting consumed by the power of the Eye, it was heavily foreshadowed after all. But I was hoping it would be more along the lines of insane psychopath becoming the new leader of the Horde as a puppet/herald of Nidhogg rather than becoming a new Nidhogg. I actually rather enjoyed the Nidhogg fight in the Aery, the sad music as he lashes out at you in his rage, the entire battle had this feeling of meaningless to it, as if you were the ones in the wrong for attacking him. Defeating him gave me no sense of satisfaction because of the truth behind the war that we learned up until that point, yet it was something that needed to be done and when Estinien finished him I knew that it was something that shouldn't have been done but needed to be.

It left a bittersweet taste to it, I didn't want Nidhogg to return as he did.