So this is where I would usually talk about the story in Bloodborne but if I did that on here I feel like I would be cheating. I played the game in Japanese and while I don't usually have much trouble playing games in Japanese the language used in Bloodborne is impenetrable and I had no idea what the fuck was going on for most of the game. I realized that there was a hunt and I had to put a stop to it somehow but almost everything about the story managed to escape me. Once I beat the game I had to go to YouTube to get an explanation of what was going on so I'll just point you in the direction of that video if you want to know the story.
As far as complaints go, I only have 2. One is the Japanese and that's really more my fault than the games fault and it's not even an issue that a native English speaker playing in English would have. Second are the chalice dungeons which are optional side areas that you can play through for certain bits of special loot. The problem with chalice dungeons is that they are all so fucking BORING. You start to glaze over as you play them and they start to feel more like a chore than anything else so unless you're going for that 100% playthrough then I'd recommend skipping them.
At the end of the day though, Bloodborne is a great addition to the Souls series and if you're a fan then you'd be doing yourself a disservice by not playing it. It's also a great place to start for a new player since it's very fast and actually quite forgiving in the opening moments although the difficulty very quickly ramps up. Check it out, I'd say it's worth buying a PS4 for.