I love the game so far but there are some brutal levels in there. I thought the Sanctum was hell, though I 100% it. And the level before it, Necrum? with the cylinders and poles was hell too. The base where you need to defend 400 went on for far too long.
I think some of the level design is brilliant, but its the controls and AI not always working that makes it more infuriating than it should. Dying is not always because of a lack of skill but the game not working as intended. There was this pole far in Necrum, you can't reach with a single jump for some reason while all others can and the distance seems to be identical. Double jump those things is extremely loose unless I do it wrong. Checkpoints are generous, though looting everything again first is annoying. I wish that would persist. I tend to jump over flags to loot, and then hit the checkpoint. Or I return to a previous one if its within reach, and reactivate the latest.
Another issue I had is that I apparently played a level via level select (the current level, even if you didn't finish, is on there). It doesn't move the story forward so I had to beat it in story mode again. Though you can ignore everything if you had posted a perfect score already.
But all in all this might be my second fave game in the franchise since I never played the old ones this much. I usually gave up at some point or went back really late. Munch aside which I felt was the most fair game in the series so far. Soulstorm has a shit ton of checkpoints and I like I can sometimes use items if i'm stuck (you can completely eliminate enemies with the right stuff). I think Munch is my fave.