The first season of Ore no Imouto ga Konna ni Kawaii Wake ga Nai had a lovely premise because of the complexity of relationship between characters. The second season just drops all the ambiguity and complexity in favor of giving us some brother/sister loving. Where in the first season it may have been some attraction that both sides didn't acknowledge or let interfere with their lives, here it is the driving force behind everything.
It is a shame that Ore no Imouto ga Konna ni Kawaii Wake ga Nai ended up as a harem with a felling of impending incest all the way through as the main theme. The first season was about a brother helping his sister work her way through some issues of growing up, from budding sexuality to balancing hobbies outside the norm with her friends, and the people they met on the journey through it all. The second season has all that finished except for the unresolved sexual tension between people. That in itself is not the problem, as a different direction could have helped the show grow... but instead, it feels more self-congratulatory than anything else.
As much as incest creeps me out, I can't say that the undertones didn't work in the first season. And I'm not saying that the second season is terrible. Actually, from a plot perspective it is somewhat better than the first. The characters get more depth to them as well. And yet, the new characters are more or less meaningless, there are no new issues, and therefore Ore no Imouto ga Konna ni Kawaii Wake ga Nai loses a lot of its strength in favor of giving us a retread of the familiar from a different angle.
Like any Harem, there are other girls and boys that get in the way. It is the source of all drama. But sadly, this heavy handed approach goes against the light hearted nature of Ore no Imouto ga Konna ni Kawaii Wake ga Nai, and the vision that made the first season so memorable cannot exist in these circumstances. Perhaps the real tragedy is that the first season struck such a clever balance. The second season trying to mix things up was a brave choice... which unfortunately backfired.
Writing (Story and Characters):
Ore no Imouto ga Konna ni Kawaii Wake ga Nai in its second season takes a very different approach to the writing than the first. Gone is the light hearted innuendo and replaced with outright interpersonal romantic drama. The surprisingly fun character interactions don't hold up as the center of the plot anymore as they take the back seat for the central theme of little sister loving. Not that the theme didn't exist in the first season (after all, the little sister is addicted to h-games centered around relationships with little sisters), but it is shoved down the throat of the viewer.
Plotwise, Ore no Imouto ga Konna ni Kawaii Wake ga Nai has a stronger second season than the first. This is not because it does anything well, but rather because it does things badly. While in many ways, it is terrible, heavy handed, obvious, unsubtle and so on... it is structured like the games which the sister creates and the gothic loli writes. It's actually quite brilliant that way, that the series eventually becomes the trigger for everything that happens in it. Of course, that is more of a meta thing, rather than an actual story, and doesn't make up for it being subpar.
Characters in the second season get a lot more development. It just isn't interesting and loses the a lot of the unique charm of the interactions of the first season. The gothic loli steps out of kuundere shell and becomes more well rounded, and becomes yet another quirky middle-school girl in a show where the majority of the cast are quirky middle-school girls. Seriously, I get that humanizing characters is important, but it loses that basic outrageousness that made the cast so unique.
Well, Ore no Imouto ga Konna ni Kawaii Wake ga Nai ends in what is the ultimate conclussion of the first episode of the first season. Unfortunately, the second season forces that. The writing ends up forcing the point rather than an organic continuation of the feel that made the first season so special. Trying too hard to get a conclusion when the show was at its best without one proved to be too detrimental. The story is better, the characters more fleshed out and human, but the writing just less special.
Art (Animation and Sound):
Just see the notes on the first season. Nothing has changed, except for more of a relliance on musical sequences to help skip through a plot faster.
Overall:
I can't help but think that the second season ruins a lot of the good things from the first. Ore no Imouto ga Konna ni Kawaii Wake ga Nai ends up on a sour note after a strong first season. Unfortunately the conclusion ends up a sour note for a series that had all the makings of something truly special. My recommendation is that you just watch the first season and leave it at that.