This 2006 summer anime movie definitely had its moments, but remained naive at parts. I have heard, however, that those who have read the two-book fantasy novel appreciated the movie much more. Just for the record, I have not read the novel, but my wife tells me that the novel has more adult audiences while the movie seems to want to target kid audiences as well.
Visually, the art is nothing spectacular, albeit using soft pastel colors... fitting for this dream vision fantasy setting. There is one feel good pop theme song (Aquatimes?), as well as Wentz as one of the voice actors for the Japanese pretty boy fans (my wife and her mother).
The story takes a simple good-versus-evil formula and puts it in a surreal fantasy world representing two boys' personal struggles to cope with reality. I particularly like the adventure style that is lost in many fantasy pieces today (too busy showing off the visuals). I have the feeling the book is more detailed in this respect, and the anime seems to skip a few of the earlier adventures, I suspect, since there seems to be some holes in the story/character development. Despite that, my eyes were not entirely dry throughout the whole movie.
That said, there could have been more development in some areas... character development, relationship development, battle action, more use of creativity while in a fantasy realm (no doubt covered probably in the novel). For a more sophisticated audience, you might leave feeling somewhat unfulfilled.
As far as an anime for kids, it's got a good message and good enough characters to deliver that message. In the end, it is not bad at all, and if you are an anime fan, it's worth a look though it may be forgettable.