Haruka and Sora Kasugano are fraternal twins that lost their parents in an accident. They decide to move from the city to a small rural town that they once spent a summer vacation with their grandparents. Many memories that Haruka had once forgotten have returned.
The animation looks good and it has some decent character designs. The voice acting is well put together and the sound track is alright.
This anime has a lot of sex scenes. Some people may end up thinking that this should have been a hentai, since it is based off of an eroge. But the subject of sex is done is a serious matter and not a damn joke.
The anime suffers in the pacing department. This anime is 12 episodes long and it wouldn't be a problem if it was aiming for a generic "lets hope we get a second season" ending. However, this show has multiple stories that branch out to alternate timelines crammed into it. So, it ends up being rushed and the only way to fixed this is to find a chart that follows the multiple timelines. If this anime had 24 episodes and dedicated 6 episode per arch, then that problem would be fixed.
Their is another thing that really pissed me off about this anime, the omake(extra)episodes that appear in the end of each episode. These are silly 2 - 5 minute long and they are loosely following the maid's storyline. This was a terrible idea to include them at the end, because it takes you out from serious episode you just watched. If this was just its own thing as a DVD extra, that would be great.
This anime has incest. Personally, I find that gross because I know what it is like to live with a sibling of the opposite sex. If you are into that, then good for you.
In conclusion, this anime is decent for what it is but the subject of incest is a big turn-off to many people. If you want a more complete experiance of Yosuga no Sora, then play the eroge it's based off of.