The game has many positives as you can read in the other reviews, but it also has one big problem. Big part of the game is just going through places you have already explored.
You missed one small entrance? Well good luck you are gonna wonder around the whole area trying to find it. Have you died? It does not respawn you on the closest healing place, but at the last one you healed yourself, which could be on the other side of the map. Have fun getting back. Also some parts of the environment are locked from you unless you get an upgrade to access them. Which you get after hours of playtime and do you now remember at which exact spot it was? No, so you have to go through the entire segment again trying to find it. But you can also buy marks, to note then on the map. Well, after you buy them it will tell you that you have just 6 of them. Which you will use up in like 30 minutes. And this sort of thing happens on and on...
The exploration part of the game is extremely fun, but it is only like 30% of the gameplay, the rest of it is just a chore of getting to a specific place.