I think the actual heart of story and detective work, the pure narrative design, is actually great. It probably got a couple of points up for that alone. The core loop of solving mysteries and "researching" works really great and can be pretty fun.
A 5 from Edge means "OK" or "average". It doesn't mean bad. It's probably relatively a 7 from somewhere like IGN.
Sinking City is cracking imo. To each their own of course. But if you're in it only for the best Lovecraftian detective gameplay around, it's a treat. Lots of sub-par stuff around that core. Deffo overstretched/overambitious.
If you do an iota of research you'll find out that Respawn have really regretted going with that slice for the demo, because everyone who actually saw the game in action said it looked like an awesome GoW/metroidvania style RPG adventure thing, while the reveal painted it as a mediocre on rails action game.
