I'm going to go off on a short rant here. I haven't actually played Symphony of the Night as I lack a PSOne, so it's not my fanboyism sustained from playing other games that's leading me to defend DS Castlevania, but it's DS Castlevania that's leading me to assume that the others are so great, because I enjoyed them so much.
It seems, anyway, that DS Castlevania is getting bashed only by the core fanbase not because it sucked as a game, but because it strayed from the traditional style and not in a way the fanbase is prepared to applaud. I'm gonna go ahead and admit that the storyline in both games was horrible, particularly in Portrait of Ruin. But storyline, generally, has never been the driving factor of Castlevania games in the first place. And there are so many great games out there without a story to speak of. Mario and Metroid come to mind. I'm willing to forgive the game for a lackluster story as long as the rest of the game is a ton of fun.
In my opinion, Portrait of Ruin has the best areas of any Castlevania game I've born witness too (admittedly a limited amount, but I've played some of the older ones on emulators). Each area was remarkably different from one another- the Sandy Grave looked nothing like the Nation of Fools. As opposed to DoS, in which pretty much all of the areas looked basically the same, excepting maybe the Subterranean Hell. If DoS can serve as an example for other Castlevania games, then PoR had some of the best area variety of any Castlevania game. If it can't, it's still up there.
Enemy design was fine, I don't see why people are complaining. The boss fights especially were awesome. The Beheaded Knight was one of the coolest boss fights I've ever seen.
My point is, here, that Dos and PoR are both great games in their own right, the only complaints that can be made about them is that they've strayed from the style everybody here is so used to. That doesn't make them bad, it just makes them different.