Let's be frank at the beginning was fun to infiltrate and kill groups of orcs, captains and chief war but eventually it becomes tiresome even with the power obtained by unlocking skills that once used we feel all powerful.
So why such a good rating? By what may easily override the qualities seen games.
First the famous Nemesis system that is fun and adds a nice concept when enemies: they remember you react to your presence and out replicas based on your "common past". It does not change the face of the world but worth quoting.
Where it becomes interesting is the stage setting and atmosphere: Mordor! We live in the middle of the land and its wildlife (which often wants to kill you) and flora (you eat to heal you) in an atmosphere of doom with orcs everywhere, mankind in slavery, deserted land ...
Another big plus point of the universe there is the story that I will not tell to avoid spoilers. Besides the part of the hero who goes in search of revenge (theme explored millions of times) we learn details, intrigues, and new unpublished parts of the Tolkien universe are explored.
In summary this is a good surprise and a purchase totally sure if you're a fan of the Lord of the Rings universe or this kind of game