Well, OoE is Castlevania, so it makes sense that it would be a Castlevania-like experience. But personally I had a rather unique experience playing the game, mostly due to difficulty. It was incredibly hard, and I appreciated the challenge. It didn't feel like PoR at all, more like Contra 4. (well, maybe easier)
I always appreciate some improvements to. The art style is awesome. Some of the best, in fact. It's funny how these great character designs clash so vividly with the absolutely godawful designs in Judgement.
Otherwise though, you're right, it's not too different, but that's not really a reason to hate a game. That's rather like going to Burger King and getting annoyed that you're getting fast food. If you want a different game, play a different series.
Developers too often try to innovate to create a different experience anyway.