The way I see the albums...
BNW - Perfect comeback album, all classic-sounding stuff, a reminder of what Maiden used to be. They learn to walk again.
DOD - Once they've learned to walk, they learn to fly! A lot more of diversity, unusual styles, long epics with no chorus repetitions at all, an acoustic song, and some forgivable lesser tracks.
AMOLAD - They go all the way on the prog side, a strong album of course but while being almost a semi-concept on the lyrical side, the mood is consistent so if you don't like it 100%, the album could drag for you.
TFF - A lighter approach, all good songs again but the formula starts to wear thin. Once again a rocking opener, the ballad, four (five!) epics in a row etc... good, experimental but not groundbreaking.
TBOS - A new approach, the trademarks are there but they're more experimental, unleashed, and inspired. The most grandiose title track since Seventh Son, and the absolute unique masterpiece of Empire of the Clouds. Long and yet enticing.