Some first impressions (no spoilers):
I played some yesterday, and maybe I'm projecting, but it's definitely got that same feel that DkS had (and that was missing, in my opinion, from DkS2), even with a completely different setting. The convoluted, interconnected world (or at least the first area) is back and beautiful. It's pretty overwhelming when you step out into the streets and see all the buildings and narrow paths (think lower Undead Burg, but even more confined space). Yharnam really feels like a city.
The game, while quicker and more fluid than the previous titles, to me, seems much harder. It could be because I'm out of practice or maybe it's because of the weapon I chose to start with, but the first boss I ran into has put up a roadblock that I can't quite get through. Of course, I'm still learning his movements, but I hope to get past him soon.
Weapon variety and placement appears to be pretty low. I've only found one weapon other than what I started with so far, and that was even pretty well hidden. The pressure and atmosphere of this game is leagues better than DkS2. So far I'm really impressed. I don't know how it'll fair in the long haul, and I'm still unsure on build variety, Co-op, and PvP, but I definitely have no regrets in making the purchase.
The big downside, for me and a lot of people it seems, are the loading times. They are pretty bad. If you die, you can expect a solid 30+ seconds of staring at the words Bloodborne on a black background. Not sure why they abandoned the item description loading screens, but those would make the wait much more bearable.
There's still so much more to learn about the game. I'm surprised I've managed to keep myself pretty well in the dark about everything. I only recently, within the last two weeks, started checking up on how the game was shaping up.