I really like this manga. I could write several essays about it. More than a sports manga, it's a philosophical manga using a sport as a device to illustrate different mindsets towards failure vs success, process vs results, and internal vs external validation.
The movie is kind of a questionable adaptation that leaves out important scenes and moves other scenes around in ways that don't really make sense, so if you were not convinced by it, please give the manga a try. If you liked the movie you should also definitely read the manga.