Yeah, gimmick bosses in DS are a thing. So are gimmick deaths - like when you're crossing the bridge and drake lands on it and crushes you, the other bridge where he breathes fire, Scaleless killing you no matter what, etc. It's frustrating, but it's part of the appeal. You're like an ant taking on decaying gods - the only thing you have going is that you can die again and again and again and again...
No reason to be defensive about BB though, the other guy I was talking to about it wasn't. It was a great game, but yeah, there was stuff I didn't like.
I also agree that it's great it's not another DS game, you do feel like a different being while playing as a hunter. I still found it silly that you could regen as much life as it allowed you to though, at least when I was using the saw cleaver. It felt a bit too much like mashing in fights was rewarded; I'd be dancing around, picking my shots, but then be like, "hey, fuck it, I can just trade with him anyway". Obviously this isn't true of all enemies types, but just something that came up kind of often.
My main gripe with the bloodvials was actually two-fold: the rate at which you could heal and how many you could carry. If you healed slower and held twenty, that'd seem cool, or healed just as fast but only held 10. It just felt like a lot.