The chapters are simply too long to read more than one of them in a single night, and oftentimes we would need to split chapters across multiple nights.
He gets into a relationship with his crush Cho Chang, but given that Chang was previously dating Cedric things do not go smoothly.
Due to Umbridge's tyrannical rule, he forms Dumbledore's Army, a group of students who practice Defense Against the Dark Arts in a practical manner, which was expressly forbidden. Harry frequently gets detention with her, and is forced to write the line "I must not tell lies" while a magic quill carves this same line into the back of his hand. All of that pales in comparison to the climax of the book, so follow this point.
I've tried to come up descriptions for the voices I used for them here.
series gets darker with each successive book, and that's no different here.