What can I write that hasn't been said already?
I'm usually not one to write reviews as I believe that people have already said what I wanted to say. And possibly in a better way than me.
But...
This anime moved me so much that I really had to do something about it! It is definitely recommended. You will laugh, sometimes really hard. But you will also cry eventually... Episode 18 did me in to be honest. It's one of those series that as you go forward to see the next episode you're thinking "Why am I doing this to myself?", barely holding tears.
But this is the best thing about it. The characters feel so real. You experience what they're going through. You feel so many things. You feel exactly like Tomoya feels. You are happy, you're sad, you hate him but then right when you have lost hope come the catharsis.
I can't write anything else. It is really a piece of art. If you are going to watch one anime, watch Clannad and then After Story (it is one anime :))! The only reason why I give it an 8 in sound is because of the annoying ending theme. :(