There, now that I have completed the game (took my sweet time with it), I can honestly say, this was a fantastic game, better than it's predecessor. But let me review it like a proper game, as it deserves.
Gameplay: 9/10
There is not much to say here other than it was great. Aside from a little wonky controls (attacking down while crouching didn't work 100 % of the time) and one abominable room in the Clocktower, with the Medusa Heads and the climable chains, the gameplay was stellar. The difficulty was just right, not too easy, but never feeling as if it was impossible. Some bosses (like the Necromancer once you walk past the beams) were too easy, but the majority of the bosses and all of the enemies were well scaled from a difficulty standpoint. The Aura Blast system, I was not fond of and found little use for it despite some mandatory parts the game forces you to use it. The only other negative critique in gameplay regard would be some of the items, like most rings and pendants, for example, I found to be completely useless. The majority of the weapons obtained were an upgrade and only twice, I found new weapons that were of no use to me whatsoever (not counting the Le Carde sword, but meaning Tyrfing and Nothung). However, this did not affect the enjoyment of the game negatively.
Graphics: 10/10
Aside from two aforementioned slight graphical issues, which I didn't even notice in my own playthrough of the game, the graphics were simply stellar. The sprites all look wonderful, the animation is fluent and the effects of flames, beams, shadows and the like all underscore the atmosphere of the game perfectly. The only, very, very minor complaint I have was that there was no working windowed mode and that the opening and closing of the menu and map took maybe a second too long (limitations of the engine, I imagine). Nothing that took away from the enjoyment or the rating of the game, however.
Sound: 8/10
The vast majority of tracks, both original and arranged/remixed I found to be excellent. Perhaps I would have liked a few more classical tracks, such as Vampire Killer or Beginnig, but the decision to not include too many original CV tracks was probably a deliberate one and understandable. The voice acting was, for a fan game, good indeed, though perhaps not done as professionally as I would have liked, given that everything else was done in such perfect detail. However, none of the voices were worse than "average" and nothing ruined the atmosphere. The only other minor complaint is that sometimes, the music and the sound effects were too loud and overshadowed the voices, making it difficult to hear what they say (for instance, the fight against Anna von Viltheim is pretty noisy, making it difficult to hear what she's saying sometimes). All in all, the music is fantastic, the voice acting satisfactory, especially for a fan project.
Story 6/10
Now the story is the only thing I found to be average. Granted, Castlevania has never had a strong story, but some points in LC2 seemed to not fit quite right, in my mind, at least. I, for one, would have left out Alucard completely (though I understand that, given the opportunity to have Robert Belgrade in your game was probably a chance you just couldn't let go without including Alucard), because at the end, he served little purpose. Indeed, his awakening prior to Nocturne in the Moonlight/Symphony of the Night doesn't really fit, to me - but if Alucard had to be included, I would have liked his involvement to be bigger, with Efrain being handed the Alucard spear (and Efrain using spears as main weapons throughout the game) in the game proper, rather than it being mentioned in the epilogue as a mere mention (unless, of course, a third game LC3 is in the making which would make the adventure in the letter by Alucard the central theme). The corrupted nobles were a good touch and a nice way to have aristocratic villains without having to rely, recycle or change already existing CV-characters. Efrain could have stood a bit more character development, or any dialogue really, but having a silent protagonist was probably also done on purpose. Not having Dracula as the main villain made sense, as this game is intended as a side story, but a few more mentions of him I would have liked a lot. Having Lucifer as the main villain was odd, in my opinion. Although he does address Dracula as "Lord", I would have preferred it to be more explicit that Lucifer is just another servant of Dracula, rather than something like an equal or even superior.
Still, despite these complaints, the story set in a different part of a world, with a corrupted group of nobles who doomed their people to a grisly fate worked well and the atmosphere of having to roam the lands (which was very reminiscent of CV2 and Stolen Seal/Order of Ecclesia) was very enjoyable.
All in all, the game was excellent and whatever complaints I have are very minor. The only reason I voice these complaints at all is because of the high quality standard of the final product and as such, I feel it deserves to be rated and reviewed like the professional game it is. Will definitely play this for a long time to come, again and again. Thanks to the team for giving the fans this revitalizing cup of Castlevania-water in a dry desert left behind by Konami.
Overall rating: 9/10
P.S.: Picture of my save file for those who care/want proof.