Actually he's rather sweet, albeit with a cold edge. Those reviewers who have found that a disappointment should go and watch The Day of the Doctor again. He was rather sweet with a cold edge in that, too, so this is entirely consistent with what we have seen. If there is a fault with the expectations of this character it is Steven Moffat's for suggesting the War Doctor was some kind of terrible monster in The Name of the Doctor and then failing to deliver on that promise in Day.
Symphony of the Night's instruction manual and cutscenes tell us that Alucard is Dracula's son — and therefore a vampire — but virtually nothing occurs to support this...Moreover, Alucard is popularly regarded as an anti-hero, which is a little silly and not at all correct. So he is a vampire (ostensibly, anyway) fighting against demons. Okay. Do any of his actions in the game or his interactions with the rest of Symphony's cast suggest any conspicuous flaws in his character? Does he commit unjust acts for the sake of a greater good? Can he be best defined by a striking deficiency of one primary virtue, or otherwise by some fatal moral failing? Or is he really just a typical goodguy hero who happens to dress like a badguy villain?
...Characters rarely have to make difficult choices or deal with the repercussions of said choices: they seldom if ever make mistakes that lead to hurting themselves or others, and nobody is ever called out, hurt by, or otherwise inconvenienced by their own flaws. Though authors often give protagonists a “token flaw”, it is always glossed over and/or thought of as cute or quirky instead of a legitimate shortcoming.