Oliver Stone’s new movie is not as much fun as the previews — which leads me to think that the optimal format for a Bush biopic might be a music video — and most of the performances are pretty bad. In fact, watching it felt a little like sitting through a not-very-funny, two-hour-long “Saturday Night Live” sketch without Tina Fey. (Though “W.” does have the alluring Elizabeth Banks.) But it does a good job of putting some of Bush’s most memorable lines and episodes on the big screen, and such a wreck of a movie is rather appropriate to this wreck of a presidency. Part of me thinks it was awful, and part of me wants to see it again.