Worst to best:
Siobhan was awful -- nearly as bad as Paige last week, and she knew it.
Tim & Didi. Just boring performances of old-fashioned songs. Didi is still gorgeous and Tim still looks slightly insane while he's singing, but I liked his banter with the judges.
Katie is no Aretha. Pitchy. She has potential but still has a ton of work to do. Aaron's performance was about the same level.
Andrew - Finally! That said he's been in the doghouse so long that, if he's back next week, he'll have to do even better going forward, and I don't know that he has the confidence.
Mike & Casey were both really good.
Crystal was great as usual but a little shaky on the piano. It seemed that she was relieved when she stood up during the song, but she sang very well.
Lee was terrific.
Overall, except for a dissapointing performance from Siobhan, the night went well. Usher was a great mentor and I think that affected the kids' performances. I liked the behind the scenes shots, and with few exceptions the judges did well.
Your bottom three: Siobhan, Didi, Tim. Didi goes home.