Shadow of Mordor was a surprisingly shallow game. It feels like they made something really cool with the nemesis system, and then they had to rush to put together half a game to attach it to. And the final few missions feel like much less than half a game.
Still a fun game overall, and the nemesis system *is* very cool.
Shadow of War seems pretty promising so far, although I remember almost nothing about it from my first playthrough, whereas I remembered a fair bit of Mordor.