LoI felt like a castlevania from the very beginning, the monsters are right, the setting is right, the castle is there, the vampire is there and in the end dracula and death are both there, only thing that comes to mind that could put you off is the 3D, but that's very well made and the music and art style all tells Castlevania.
LoS is completely different, in the beginning it has the castlevania feeling, rainy night, farmer's village, werewolves onslaught and Robert Carlyle...hmmm, something doesn't fit, nah, let's keep going.
As i was saying, the beginning sets you right, battle has some new features, but that's ok, improvment could be good, but then the story starts developing and it couldn't be more different than the other castlevania, it is true that the gameply feels GoWish, but the worst part is that the story feels like a mix of Dante's Inferno(the game) and Devil may cry 3(and somehow i kept thinking stargate universe the whole time...

).
I might sound hard in my judgment, the game is fine and enjoyable on his own, but they had to slap Castlevania on it's cover(gotta thank Kojima for this... -_-), so i'll judge it as a Castlevania, so the story sucks compared to the other castlevania, the setting is so damn common these days that it's painful to look at it, the fact the bgm isn't particularly impressive sure doesn't help, i love the castlevania series because they were different from the masses, they really gave me something to look forward to among the pile of mass produced cheap stuff you can find everywhere. Kind of like suikoden was to rpg's, i don't care how many people show up brandishing "Reboot" as sacred weapon, if this is the way they intend to go with the new Castlevanias, i don't think i can follow, there's more interesting stuff to waste my time on.