There's a reason this Anime is top among big names, it's an absolute emotional roller coaster. Make sure you watch the season before, Clannad. With such amazing characters and storyline, you'll be left in tears time and time again, while other moments finding yourself happy.
Unlike 90% of Animes I usually watch, I watched this one in dub, even though at the moments the voice acting and timing is slightly off. Still a wonderful peace.
I'm not much of a writer, so I can't make justice to this story. So all I can do is recommend this to you, a thousand times over. I'm planning on watching it through again.
The season previous to this one, Clannad, is a little bit more on the boring side, but is definitely worth the watch as it builds up their characters and is essentially to understanding the full story.
Music is great, hence the 9, only thing lowering this was because the dub so... I presume it would have been better if it was the subbed version.