Just got back from watching it. Movie theater was empty when I got there about ten minutes before showtime. They had a slideshow quiz before the movie started. A father and son walked in a few minutes after I did. They left when the credits started, which means they missed a fairly long post-credits sequence.
The movie was mostly played for laughs, which is fine. There were jokes about Nightwing's mullet, sex, and passing gas.
They also showed about 5 minutes of one of the special features that will be on the Blu-ray. It was mostly Paul Dini and Bruce Timm talking about how they created Harley Quinn. (Batman: TAS clips look awful blown up on the big screen.)