Personally, I really really like this anime. (In fact, it's my favorite one as of now). But looking at the other reviews, I can tell that not everyone agrees... Well, I guess we all have our own opinions. :-/ Anyways, this review will also refer back to the first season, and may contain spoilers.
I found the story very interesting; and never once thought the anime was boring while watching it. I like the way that they make the anime last over a couple of years, rather than in a short amount of time like some other animes. But part of the reason why I rather enjoyed the story plot is because of the fact that I enjoy things that are more serious and realistic; so if you're someone that likes something silly and fun, this anime definitely isn't for you. I think that that is another reason why some people found the anime boring...cause most animes nowadays are filled with silly little moments (that are also rather unrealistic) that are supposed to amuse the watcher. Hakuouki doesn't really have any of those, so once again I suggest that you should only watch this anime if you enjoy serious story plots. Hakuouki (especially the second season) also contains some sad moments, another thing that I always look for in anime. Personally I really like sad animes as well, which is another reason why Hakuouki matched my preferences so much.
Well, I'm not too picky about art, so I don't care too much about it. The only thing I really look for in an anime art-wise is whether or not I like the style of the characters. And well, I found that the style of Hakuouki looks very nice compared to many other animes, so I immediately took interest in it. Truthfully, the only reason I started watching Hakuouki was because of the fact that I saw a picture of the style and like it.
Actually I'm not really sure what it means by sound...so I'm just gonna assume they mean the music and stuff. As far as the OSTs go, I find that they really suit the anime so I'm giving the sound a 9. The openings and endings also really suited it, and I also enjoyed them personally, so all in all I say the sound is good.
Personally, I really like the characters in Hakuouki. I like how everyone acts realistically, and how I can imagine a real person acting like them. In other animes, I constantly find myself asking 'Would a person actually do that?' because of how ridiculous they make someone act. No, I don't really have anything against that, but since I like it when animes make characters act realistic, I found myself really liking the characters of Hakuouki. Now what I see a lot are people hating on the main female character; Chizuru. True, she's not as likable as the other 'main' characters, but I actually kinda like her. Yes, sometimes I found myself saying 'Come on Chizuru! Try to protect yourself for once!', but I personally thought it was realistic at the same time since back then women were treated as inferior to men. And since Hakuouki is pretty realistic as far as the way they make the characters act and the way they stick to history, I had nothing against Chizuru for being like that. And the reason why I found myself liking Chizuru was because of some lines she says in the anime. I don't know about other people, but I like having 'favorite lines' in certain animes, so Hakuouki is no different. And some of my 'favorite lines' in Hakuouki come from Chizuru herself, which (to me) shows how she is more mature than you'd initially think she'd be.
Well, I really like this anime; there's not much to say. :3 Pretty much all the reasons why I like it so much is said above, so I don't have anything to add.
So, all in all, I would only recommend this anime to people who enjoy animes that are more serious, have a bit of violence, have sad moments, and have characters that act more realistic than other animes. If you're looking for an anime that is either silly, fun, or romantic, I would suggest you looking for another anime. Yes, there are some moments that are more happy and fun, but there aren't many of those. And yes, there is also some romance in the anime, but it comes a lot later so those that are watching Hakuouki just for the romance would be disappointed.