My thoughts.
1. High production values: The animation during the concert scene was particularly good. Considering the staff they have working on this, I would have been very surprised if it didn't have high production values. Of course, if we're going to get any wonky animation it'll be later on when the budget starts running low. Though, since they are working with what is arguably the hottest property in Japan right now, the budget on this might not be much of a problem.
2. Really good acting (from the AKB girls): Again, not too much of a surprise to me, since they did actually audition the girls beforehand. They were able to pick the best voices for the show. Amina's voice, in particular, is perfect for Anime.
3. No explanation of the setup in Episode one: I'm not really bothered by this. A lot of anime don't explain everything that's going on right off the bat. I'm sure that we'll have some sort of "history lesson" either during the auditions or the Kenkyuusei training.
All in all, I enjoyed it a lot. It wasn't the best first episode I've ever seen, but I'll definitely be back for the second one.
All that said, the best part of the first episode for me, hands down, was Takamina's hair ribbon.