If you did not like Air(tv series) you will not like this. The opposite is also true, if you liked Air, you will enjoy this series. I say this only because they are similar in so many ways (KEY made both visual novels).
Story: 7
Just looking at the story itself and removing my personal feelings, I believe that it is good. I gave the story a 7 because it acts as a double-edged sword. While it intensifies the atmosphere and realness, it also makes the effects of what goes on much more amplified. There is dark atmoshpere clashing with hope and happiness as something always seems to get in the way of the Tomoya and Nagaisa, much like the prequel. The focus of the story also gradually changes as you watch the series. And though it takes till he end of the series, there is a good ending.
Art: 9
I have always loved the art that comes from KEY's visual novels. It looks pretty and makes the show much more enjoyable.
Sound: 7
I really never thought too much about the sound, but never noticed any problems. It just was what you'd expect to get from any show.
Character: 7
Again, much like the story, there is nothing spectacular or terrible about the characters in the show. Tomoya is well thought out and always seems to be going through some difficult endeavor.
Enjoyment: 1
Just a disclaimer, I watched this series a few days after my grandfather died, so I was kinda down. While I did enjoy the prequel, Clannad: after story was just too depressing the whole way through the show. It just seemed that something aweful would continue to happend to tomoya and I wasn't feeling like that was enjoyable. The ending barely made up for the rest of the story. HOWEVER, I would say it would be enjoyable to those who have watched the prequel and really enjoyed watching it. It is a similar atmosphere and all.
Overall: 6
I tried my best to take my personal feelings out of the way, but it was just okay. The show had too many depressing moments, and while the clever jokes and laughs would be well spaced, it couldn't make up it. While I didn't enjoy the show, I know a lot of people would. I gave the 6 instead of a lower grade because I was a little relieved at the end.
