Overall, the series in my opinion would be 10, because it's my favorite Anime. Though, the story itself was very complex with all the characters connected together, and when you think about it, the story wouldn't be the same without 1 character or another, in terms of each were moral support for other characters at one point.
The characters were Nagisa Furukawa, Tomoya Okazaki [<--2 Main characters], Yohei Sunohara [Everyone calls him Sunohara, though], Kyou & Ryou Fujibayashi [Twins], Tomoyo Sakagami [Tough girl with similar name to Tomoya], Kotomi Ichinose [Childhood friend of Tomoya], Fuko Ibuki [Ghost girl who plays a huge role], Yukine Miyazawa [Storage room girl], & Misae Sagara [Dorm mother of Sunohara and other boys]. These are just mainly the characters.
Nagisa & Tomoya had a thing going on throughout the Anime, but it built slowly, but shows that if 2 people love and care each other enough, they'll last. Yohei Sunohara met Tomoya around begining of high school, nearly before the rest of them, I'm sure. He gets beat on by Tomoyo who had entered the school as a Junior while the rest were Seniors and was known to be very tough, and also made quite an entrance by beating up Gang members disturbing the peace at the school, and her main goal was ironic, she wanted to preserve the Sakura Trees, by becoming the School's Student Council President. Kotomi was Tomoya's childhood friend who he had stumbled upon her yard as a child and hung out with her until his friends teased her, but right before her birthday too, so he stopped coming and she lost her only friend, as well as her parents on her birthday. She finds out they tried to get her Teddy Bear to her during those years by sending the suitcase with it around the world, because it was found drifting in sea when the plane crashed. Fuko Ibuki was a Ghost girl who manifested herself out of the hospital with the will to grant her sister an amazing wedding whom had been a student and teacher at that school once before. Yukine is friends with 2 rival gangs and she treats them both nicely trying to calm the violence, but fails until the end where they all find out her brother, the leader of one of the gangs had died already, which put an end to their fighting. Misae is the Dorm mother of Sunohara and other guys and is highly respected along with how she was the Student Council President as a Student at that school and made sure no absences occurred for a week.

I'll stop there. Mainly, the story was well thought out, and had many rhetorical questions around it, but if you knew the answers to them, you'd understand the story more. The visions that happen alot in the anime usually at the begining of it was Ushio, the daughter of Tomoya and Nagisa in a different world, which connects to the real world. [spoiler]When she died in that world, she did so in the real world too, but used the last of her power to send the robot she made, which was actually Tomoya back in time before Nagisa died and changed the course of events so that Nagisa survives and Tomoya knew exactly what happened just there. Tomoya would've been lost in that world forever which means Ushio would've died in both worlds not being able to send him back, ending the story morbidly