I could go on and on about how great Summer Wars is, but I'll try to get straight to the point.
Summer Wars is awesome. The animation style is one of my favourites, and the movie hits a lot of the right beats. It's funny, it has action, it has drama, it's suspenseful, and it's emotional.
The biggest issue is that for anyone who's ever watched "Our War Game" (a Digimon movie) or saw the American version of The Digimon Movie (middle section), Summer Wars is all too familiar.
From "messing around" on computers, to a rogue virus/AI, to even the climactic finale, it's eerily the same. It could have just been one big coincidence, but considering it's the same director for both films, it's not. True Our War Game is just 40 mins where Summer Wars is a feature length film, but there are so many scenes that are similar that it takes away from a lot of the show-stopping moments because it doesn't feel new.
This doesn't mean that I didn't enjoy it. I still thought it was an amazing movie. It just lacked the wow factor. And I think a lot of fans who've seen either the Digimon Movie, or Our War Game will feel the same. If you haven't seen it, then enjoy!!! You're about to watch one of the best anime films I've seen in a long time. It's funny, heartfelt and loaded with action. In fact I'm jealous. Because even when I saw it for the first time, it didn't really feel like the first time.