While the game is insanely demanding - especially the first time through - it's also pretty forgiving in terms of not dicking you over when you die. Checkpoints are plentiful, and if you get killed, you're almost guaranteed to come back just before the point that gave you trouble. The puzzles are also fairly lenient, as they're designed to be slammed through quickly. Some of them are pretty clever, and the solutions aren't usually obvious, but if you've explored your environment and know how things work, you should be able to figure them out pretty fast.
One thing that isn't forgiving is the actual combat. It might be button-mashy and quick, and your combos might have devastating effects on your enemies, but they'll keep coming fast and they'll mob you if they get the chance. And in the rare instances when Kratos actually has to protect someone else, they'll often ignore you and go straight for the weaker target. Strangely, though, the fights never really feel like too heavy a challenge; like so much else in this game, their length and difficulty feel perfectly balanced. They're also relentlessly satisfying and gruesome, particularly when you're tugging the eye out of a Cyclops, or straddling a minotaur and stabbing him in the mouth.