So, Lords of Shadow serves as a history of the main antagonist of future "Castlevania games"? Or we are going to play with the bad guy from this game on? I can think in Legacy of Kain Defiance, where you can play with both hero (or antihero) and main villian. But, for a Castlevania game, I prefer the old and classic (and true) stuff.
As for the Forgotten One fight/plot...
The stage is good, and the same is for the platforming. The fight was really awesome. But, for a Castlevania game, no thanks... After read that some of us in this forums wants or expect more crazy plot twists, old games reinvented (like the Trevor one), ideas for a sequel, I just have to say that this is the end for the Castlevania saga as we know, and the welcome to a new one. Sad. I still prefer the old/classic one. Where you only fight Dracula and nothing else. Because, in future sequels of LoS, the main villian will be Dracula? Or we are goint to see Satan again? Two main villians? And, why to control you a character, if he are going to be the main villian in your game? I simply don´t like it. Somebody yes, but I don´t.
I don´t like the ending. But I was expecting such an ending. But, all that you get in your trial are going to be innecesary in the next games? Or Rinaldo are going to make the same weapons again? I can imagine, Dracula saying to the next (I hope) true Belmont: "I was once have a weapon like yours. You cannot beat me, because I know your techniques. And all the enemies that you fight, I fight them too in the past. Now we are friends. What is a man? A miserable little pile of secrets!!!!"