I was inconsolable the first time I read it. I think I was 7, and my parents had only read The Lion, the Witch, and the Wardrobe with me. They thought that the stories wouldn't have anything that would upset me and were happy to see me reading. But I read The Last Battle all at once. I had to keep reading and make sure things would be okay.
I was horrified that Shift manipulated the Narnians' love for Aslan, that Cair Paravel had been taken, when Eustace was thrown through the stable door and the worst was learning what had happened to the friends of Narnia.
I think I was too young to understand it, and now whenever we sell a set of the books at the bookstore, I tell parents to read The Last Battle before their children and then with them. I'm older now, and I understand and love the end of the books now. I know to feel sorry for Susan, even though I am convinced that she would know where they have gone and make sure Aunt Alberta and Uncle Harold knew, too, and anyone else who would listen.
And now, I mostly cry at the end of The Lion, the Witch and the Wardrobe, when they are back in the spare room, and at the ends of Prince Caspian and Dawn Treader.