I was just listening to the album yesterday. It was the first time I heard the full album from start to finish. There were even a couple songs I hadn't even heard. Moonchild was really cool.
I know people list it, or used to list 7th Son as Maiden's 'progressive' album. At the time of it's release, yeah, it was their most progressive album. But with XFactor and all the albums since, it's no more their most progressive album. I'm starting to see that I love Maiden most when there are 3 guitarists in the band.