This is going to truely be a great game once the performance gets figured out. I have a pretty powerful system and I got defaulted to 'low' specs. The gameplay side is very good. A ton of fun and similar to an updated skyrim with better combat. Highly recommend you get this.
This new Sherlock Holmes game is a departure from the previous games in that it is effectively open world. The investigations have been fantastic and pretty logical and I have only encountered one small bug so far even on the release patch. If you like Sherlock Holmes or previous Frogwares games, I would say go for it.
I've been playing Black Geyser since the start of Early Access. So far it is definitely early access (i.e. missing a ton of spells, buggy etc.) but the game is playable and is getting frequent updates that fix most of the bugs. Just based on what I've seen so far its a 4/5 but I can see the potential for a 5/5 depending on what makes it into the full release version.