My only criticism of this album is that its too polished. Had the songs been longer and varied in song structure, they would've had a longer shelf life. This is something very interesting about Mariah's songs post-TEOM actually. Pre-TEOM there were little instrumental breaks, say in between the chorus and the next verse, now its like she cannot waste those two seconds. She has to layer the start of the second verse as soon as the chorus ends, and layer the bridge as soon as the second chorus ends. (I Stay in Love is most guilty of this)
Also, pre-TEOM, there was a longer (albeit less busy) climax and resolution to her songs. On E=MC2 in particular, the climaxes feel particularly crammed into one verse. It works on songs like WBT for example, because they leave you yearning for more, but when it goes on for a whole album, the album is gonna feel like it was lacking something you were waiting for. The whole thing that makes a Mariah Carey song different from these other singers is that her adlibs at the end of a song are really natural, fluid and melodic. But its hard to notice those adlibs when they are crammed into 30 seconds, one adlib over the other, rather than one adlib after the other.
Does she do this things consciously or not? I don't know. Someone from her team probably told her that her songs on CB ran for too long, because there was an obvious change on her song structure from there. I've noticed that the songs most people here still love are the ones that doesn't suffer as much from this complex. The ones that have a proper climax and ending. These songs are "I Wish You Well" and "For The Record" Thank God, she seemed to have eased up on this "Make my song as short as possible for the ADHD people complex" on Memoirs.
Despite all these song structure issues, E=MC2 still is a very solid album. For me E=MC2 is more than just a collection of songs. It really reflects her state of mind circa 2007-2008.
This album represents a rich, successful hot single woman, out to have fun, yet still looking for love and reflective of her past sorrows, relationships and sufferings. Some songs are not that deep, whilst others are reflective. Either way, it perfectly sums up Mariah Carey at that time.