I played through the game and I honestly didn't have much difficulty with it at all - I'm actually kind of surprised that so many are having significantly more trouble than I did. Sure, sometimes a mid-battle objective change would catch me off guard the first time I saw it, or I had to restart because I wasn't familiar with a new enemy type, but I was never frustrated after a few attempts here or there.
ND is fresh in some ways, with mechanics that don't really have an analogue to other games in the genre, and for that I appreciate it trying something new. You can’t fault it for being overdone, mechanically generic, trite, or commonplace, because it’s none of those things. However, I felt like the game never evolved around of subset of ideas - or to be trite - it never seemed fully actualized to me.
In the early portions of the game, when I really got a handle on how to go utilize the linking and other systems, I starting imagining what kind of map designs I might run into using them. I was intriqued by some of the cool ideas that were introduced and I was quite curious to see how they would come together to be implemented in the later stages of the game. But the implementation remained basic, the objectives remained boring, and before I knew it the game was over.
I beat it in about 20 hours, although I barely touched multiplayer.