Rowling rises above and beyond her first three books with this fourth Potter adventure. This is where the overarching plot line of the series truly takes off, and if the cliffhanger ending is any indication, that major plot won't let up until the end of the seventh book.
I think, with this book, I can say that Rowling has come into her own. Her storytelling ability has increased greatly since the third book in the series, and the emotional poignancy of this volume also propels it above the status of a fun children's adventure into serious older-ages fare. Far from getting tired of the series, the Goblet of Fire, more than any Potter book before it, left me wishing to pick up the next book immediately, sleep be damned!