Have you ever been so engrossed in a book that if the ending isn't strong and doesn't resolve all the plot threads, you're disappointed in the whole book? I once read a novel with a deeply engaging main character I really connected with. She struggled and overcame and struggled and overcame. And at the very end of the book, the author killed her. WHAT? It's the only time I've ever thrown a book. And I refused to read anything more by that author.
You know how important it is to hook your reader from the very beginning. It's why you start in the middle of the action, plunging your reader right in so they get caught up in the excitement.
Your ending is as important…if not more.