A real lovely movie. If you're used to Ghibli movies and Miyazaki's style, then this film is for you. It's a quieter film and the pacing for the first half is a bit slow, but it picks up for the second half. Like many have said, it really feels like a personal film for Miyazaki. While there are joyful, whimsical moments (especially with the Heron, Parakeets, and Grannies), the film's themes are pretty dark and somber (dealing with death, grief, and the pain of creation). Definitely worth pondering over though.
When I left the theater, a group behind me kept asking why certain plot points happened, why characters did what they did, or why certain creatures appeared out of nowhere. One guy said he slept thru most of it. A shame. If you want something more straightforward, quick, and active; this probably isn't the right film for you. But its quiet nature will help you enjoy the beautiful visuals, music, and English voiceovers. Not my favorite Ghibli film, but still a good one.