Clannad in itself sets up the larger plotline that takes place in After Story. As you should already know, it depicts Tomoya Okazaki and his best friend Youhei Sunohara meeting new friends, particularly Nagisa Furukawa.
Speaking of characters, most of them are phenomenal. Some of the female characters are a tad bland and similar, albeit (most of them being petite, fragile, and timid, and the rest being ruthless tomboys), but you should find something to like about the personalities of all of them if you look hard enough.
The story itself is a little slow until you get into After Story, so if character development (as great as it gets in this) isn't enough to keep you interested, then you may fade out. I urge you to finish it for the great After Story, however.
The writing is absolutely brilliant. There will be times when you laugh, others when you cry, and sometimes when you cry because you were laughing too hard. For a show that made me think this deeply about life, I sure did laugh quite a bit.
The music and sound design are likewise brilliant. Go to YouTube and search for some of the OST; you won't be disappointed.
Overall this is a great anime, and the sequel is even better. It was one of the first anime series I had seen, and therefore I can say with confidence that ANYONE can watch this; you don't have to be extremely keen to the animesphere at all to get into this.
