I watched the movie prior to reading this and absolutely -loved- both medium. I would compare this with the likes of Hayao Miyazaki and his work. It has a lot of the same themes that you'd find in Miyazaki's works: an underlying element and deeper message, a "fantasy" world or mythical world that "children" ( and adults ) dream or think about, and strong emphasis on family or friendship.
In fact, I'd say this is about even with some of Miyazaki's best ( in my opinion, of course ) works, like Spirited Away.
Kenji Koiso is a high school student with a crush on a kendo club beauty, Natsuki Shinohara, and a knack for mathematics. His aptitude with numbers earns him a part-time working maintenance on the global virtual reality world, OZ.
One day, right before summer vacation, Natsuki asks Kenji to do her a favor -accompany her to her great-grandmother's 90th birthday celebration deep in the Japanese countryside. As Kenji tries to find his footing amongst the boisterous and tightly-knit Jinnouchi clan, receives a mysterious email with a long code and the message: "Solve me." Little does Kenji know what solving that code could lead to...
Without spoiling too much, Summer Wars is a very endearing, family-oriented movie that has a little something for everyone: a person who doesn't have a family, big families, and being accepted into a family despite being an outsider.
I'm not much for things that get TOO sappy, but there's some real heartache towards the end.
Overall Rating: 5 out of 5.
Recommended for: Absolutely everyone.