Ginsu, there was no notice which movie you'd see until you were in the theatre, so we skipped the movie and kept the tickets as souvenirs. I had a three-panel reel of Okkoto from Princess Mononoke on my ticket that I was unwilling to surrender! Studio Ghibli is outstanding. If you are ever in Tokyo, hop over to see it - it's barely 15 minutes from Shinjuku to Mitaka, and it's about a 10 minute walk from the station. Just remember to buy your tickets in advance before you leave your country; on the first trip to Japan, I waited until I was in Japan to buy the tickets and they were already sold out.

Even leaving aside Studio Ghibli, Mitaka was probably one of the nicest districts of Tokyo I've ever seen. And in random Japanese fashion, the corner store near the Studio sells birds of prey. I couldn't figure out how to fit a raptor in my carry on, so I had to pass on the opportunity.
The arcade was definitely cool, but it's fairly expensive. We played some House of the Dead 4, and it was 100Y per credit, 2 credits per play. The Mario Kart racers were the same situation; 200Y per play. The taiko drum games were probably the most fun - basically, it's simplified rock band drumming - but still 100Y per game. If I were not on vacation, I'd probably balk at that price. As it was, my wife and I dropped about $40 on just an hour at the arcade.
An interesting feature was the apparent 'save' or 'continue' option at the end of some games. When you completed levels on the taiko drumming game, it flashed a barcode. You can apparently snap a photo of the barcode and continue from where you left off at some point in the future, and presumably at any arcade you visit. That was a neat feature.