First off, I liked this this movie. I watched it a second time over the weekend and thought it was pretty enjoyable. You can tell the director's main work is music videos. The musical numbers and the flourishes like the animated flask and the cuckoo clocks over Dre's bed show a real familiarity with creating a scene and mood. As for the plot ... well, that was kind of sparse. One thing that bugged me was that I didn't really get why the club was so important. Why it was so important for Rooster to take it over, and exactly how much in debt he was. I thought Terrance Howard taking out Spats and Ace kind of came out of nowhere, and I never really got a sense of him as a villain. I'm also not real sure why this was set in the prohibition era, aside from just a stylistic choice. Sure, they were smuggling hooch into the club, but I didn't think there was ever any real concern about the cops busting them up. Overall, basically, the stakes felt pretty low.
To me, Dre seemed not so much low energy, as just sad and emotionally burdened. I liked his performance, and his chemistry with Angel/Sally. Their story was probably my favorite part of the movie. And the end with Busby Berkeley-esque musical number at the end and through the credits. I also felt the song Dre does while dressing Angel/Sally's body for burial was the weakest, but the rest of the music was really fun. Very Outkast.
And final thought - what is with prohibition-era musicals and scoundrels named Rooster? (ahem, Annie).