I had no idea everyone hated IV so much. I thought it was a blast; it's a tad on the easy side, yes, but that isn't necessarily a bad thing. After the NES installments, I appreciated the breezier pace. Also, while I'm probably alone on this one, I like how it's completely linear, with no branching paths or extra playable characters. I prefer straightforward when it comes to Castlevania.
I only played Bloodlines on an emulator. Seemed alright. Nothing special, but nothing to get overly critical about either.