I found it easier in terms of simply surviving and getting things done, (playing on the default difficulty level). This might have been due to all my experience with the previous game translating to the new one (very similar gameplay obviously) in addition to the additional tools you have in this game. You do start out some what "depowered" from the 1st game but you eclipse your former level of power as the game wears on.
One thing that's true of both games in terms of fighting warchiefs is that it makes a huge difference if you exploit their weaknesses vs trying to fight them strength against strength. They hit harder than you, they have more health than you, so you need to exploit their flaws.
In this game one of the easiest and safest ways to take down a captain/warchief is to freeze him (assuming he's not immune to frost). This can be done in a number of ways but regardless once he's frozen he's helpless but to just stand there taking hits. Which allows you to build up your might meter and unleash a powerful attack on him.
One note on death is that while you can get to a level of mastery where you basically never die, the design intent isn't that death = you failed ha-ha you suck. Your "deaths" are a thematic part of the nemesis system which is part of why Talion was made so fragile relative to his foes.
Also, later in this game you can fly around on a drake and incinerate everyone, so that's fun.
I judge everyone based on their sig. If you wanna judge me for that, go ahead.