I'm almost done with my first playthrough. The only bosses I have left to clear are the final one, the TLB, and a handful of the chalice dungeon ones. Aside from that, I unknowingly screwed myself out of some covenants/sub-quests, so I'll be sure to experience all that in NG+.
Overall, I'd say this is the easiest "Souls" game I've played so far, and the only one I haven't played yet is Dark Souls 2. I decided to stop leveling up once I hit 60, and yet I still feel like I'm over-leveled. The apparent difficulty is neither good nor bad really; on one hand a higher level of challenge would feel more rewarding and add a bit more length to the game, but on the other it makes it less of a drag to experiment with new builds and makes the game more fun to replay. Maybe it would be better if the bosses were a bit more challenging to fight, since the majority of them are push-overs which I've cleared on the first try, and the harder ones only take a few retries (only to become mostly push-overs themselves once their attacks are figured out). And no, I did not use guides to help me with the bosses, nor did I summon co-op partners.
While I feel that some of the design changes are a step back (not being able to rest at lamps, vials instead of estus, co-op/PvP system), there are also a good number of new things I prefer (guns instead of shields, dashing while locked-on, more streamlined upgrade system, charge attacks). I also like that armor is more cosmetic, so now I can just wear what I like, instead of stuff with good stats but unappealing looks. Although the multiplayer matchmaking system is definitely less than optimal, the gameplay changes/additions make the PvP matches themselves a lot more fun to engage in imo (though I've only played 6 matches so far). To elaborate on the estus vs vials issue, I wouldn't say that estus is necessarily better, rather that it merely "sucks less". To be honest, I don't think any Souls game has done it right for my liking. I would much rather have all major healing items disabled during PvP matches. Speaking for myself, players being able to use healing items during PvP just causes the matches to drag on for way too long.
A couple of other things: this game has a lot of optional content, and most of it feels really easy to miss. Related to that, I know I mentioned that I missed out on some covenants and NPC sub-plots, but the NPCs in Bloodborne felt much more empty and boring than in other Souls games. My opinion on the latter might change after NG+, but it felt like the characters in other Souls games had way more personality and were easier to find/talk to, which added a lot to the story/lore of the settings.
Overall though, I'm enjoying Bloodborne a lot. But Dark Souls is still my favorite Souls game so far, mainly because it's the one that reminds me the most of King's Field.