A short Bloodborne review from a long-time From Soft enthusiast.
Mechanically, Bloodborne was pretty good. It fixed a lot of the complaints I had about DaS2, most importantly the lack of fluidity in combat mechanics and lack of frame precision w.r.t. the hitboxes (things that were done correctly in DaS1 and DeS but for some reason not in DaS2). The trick weapons and new combat mechanics (guns, etc) are a pretty cool twist on the Souls' series combat system and I enjoyed it a lot. All enemies felt quite different from each other and their AI was quite good, making for a lot of interesting and challenging encounters.
Unlike normal enemies, the bosses were for the most part quite bad. I think this is mostly because the increased combat speed didn't allow for the careful and meticulous "studying" of boss moves and boss strategies that was prominent in previous installments of the series, and also because the game does not allow for a lot of variety in the builds, so there are really very few ways to approach each boss. This is not true for all bosses: interestingly, the humanoid bosses, incl. the Shadows of Yharnam, Gascoigne (sp?), and the final boss, were all quite well designed. This makes me suspect that the challenge of designing Lovecraftian abominations and figuring out their movesets also worsened boss quality in the end.
The Chalice dungeons, bloodgem mechanics, limited silver bullet use, and balance in general are where the game's mechanics are lacking. This affects both multiplayer and single-player experiences, and it makes some parts of the game a chore to be honest. The Chalice dungeons in particular are a frustrating crawl to get through and they left me very bored and unsatisfied, their difficulty primarily being derived from increasing enemy HP and damage, and not from adding any genuinely new challenges to the game.
The multiplayer is very lacking. It's clear it wasn't the focus in this game, and From Soft gimped the PvP experience by silly ideas such as the bell maidens, 30% max HP deduction for invaders, lack of counters to healing in combat, limited silver bullet use, by forcing us to farm for bloodgems, and for a multitude of other reasons. Even though the combat mechanics are precise and fluid, the lack of build variety, and the slew of annoyances and design problems with the game make it inferior to all games in the Souls' series in terms of multiplayer, including even Demon Souls.
Atmosphere and story-wise the game is (IMO) one of the stronger entries in the series. The story is interesting and (for the most part) well-presented, and the writing and exposition are very enticing. Although this isn't apparent on a superficial level, Bloodborne's story is similar to Demon's Souls, and it is equally inaccessible and open to interpretation. This is in contrast with Dark Souls which had a (relatively) more straightforward and accessible story, and also more closure. Even more-so than Demon's Souls the game relies on metaphor and symbolism in its presentation, which is an interesting gambit on part of From Soft. I would say this gambit succeeded for the most part, but the symbolism sometimes felt excessive and over-the-top and left me with a murky, dissatisfied feeling.
But like I said, overall the writing and atmosphere are on par with Miyazaki's other two games in the series (and definitely much better than the Dark Souls 2's fan wanking), although it has different pros and flaws.
Graphica- and content-wise the game felt short and there was not much variety (I felt) from the art design perspective. All areas felt equally grimdark and used the same artistic gimmicks as the other areas and while the gameplay differs significantly enough between them, too often I felt like I was exploring a different sub-area of some overarching level rather than exploring a new area or level entirely. There are some exceptions to this, namely the Nightmare levels, but because the game has much less content than other entries in the series this is, in my opinion, inexcusable, and I hope it will be addressed in future expansion packs.
Like I started saying earlier, while the enemies feel quite varied, the builds do not, and this also affects playability and replayability. I'd like to say again that most non-humanoid bosses felt quite poorly designed, and it seems like the same tactics worked against pretty much any of them. This is in contrast to the quite good humanoid bosses, probably because they were easier to design.
Chalice dungeons I already talked about. They're pretty bad.
In conclusion, from a setting/story perspective and as a mechanics demo that can be expanded with more content later on, Bloodborne is quite good. However, it's heavily lacking in a lot of other areas and ultimately I don't think it holds up to other Miyazaki games in recent years. Certainly it's not as good as DeS or DaS, although I'm not sure how I would rank it compared to DaS2.
Some people could argue that it's wrong to compare Bloodborne to the Souls series and have the same expectations for it because it is a new IP. This is quite frankly bullshit. Both mechanically and story-wise this game is Demon's Souls 2 with guns. It might be a new IP, but it's a spiritual sequel to the Souls series in every respect.
Overall I give it a 9.97/10 for "quite good" based on the international IGN scoring system (tm).