I am a huge fan of Christina Aguilera (been a fan since 2000) and have all her albums (even seen her in concert.)
I just got the album, and I'm listening to it right now. It's the third track on the album, and it samples Michael from that era. She put a lot of his vocals in there, so it's almost like a duet at times (really young Michael and 30 year old Christina.) The new song's melody is also based around the old MJ song.
I know Christina Aguilera is a huge MJ fan, and she did him justice by not messing with his vocals and including him in one of her songs. I can't wait to hear this on the radio!
Also, as far as the rappers go, they are only on a few songs. I think this is her best album since the albums Back to Basics and Stripped.