In honesty, I would give it 4.5 stars. I'm not a casual gamer but I can go hard in the paint on certain titles and I did exactly that with this game. Story progression and elements are superb and kept me interested and coming back but the only MAJOR ding to this game (and thus my minus .5 star rating) is the gameplay in relation to certain boss fights and missions.
Some elements of gameplay can be downright punishing even on normal mode which ultimately can lead people to become disheartened and thus drop the game. The story is what made me keep coming back to the game and ultimately, once I reached the end I turned on some of the gameplay assist modes that help ease combat. Dying with the character on a hard mission is to be expected but doing so over and over again can be disheartening and downright punishing, even for players (like myself) who like to play on the hardest mode. Some strategies just flat out didn't work when it comes to predicting movements and executing combat strategies after playing (and dying) and some missions so it made it painstakingly repetitive. Would love to see a 2nd game but altered gameplay modes that don't absolutely obliterate you.
Overall, I would recommend even seasoned gamers try some of the gameplay assists because doing missions over and over again over long periods of time can get frustrating ultimately.