I cannot say I am having fun. Sneaking around BTs also means staying in the rain, I have no idea how do the granades work, the game punishes mr for trying anything new, because new takes time...
Early on you only get waste grenades from the shower and toilet. Those will make BTs move, but won't get rid of them. Don't worry about S-ranking deliveries early on. The game opens up a lot when you get to the second region, but that's probably at least ten hours in.
It's definitely not for everybody and you really have to slog through the first 10-12 hours to get to what I consider the good part, which is not good design IMO.