I gave it a 2
Played on easy first, plus collectables. It was very easy, and the collectables are not very hard.
Then played on Brutal, took me two sittings, it was very easy too.
Kill trophies are not hard, plus you don't need to farm for it, you just need to track what you need.
Survival is easy, only failed the 5th one and had to redo the 3rd for a piece of photo.
Skill trophies are easy since there is no need to farm for them.
Very enjoyable game