Maybe that's the misguiding thing here - it's not the perfect music album, but it's huge already. So you cannot concentrate on what she is trying to do. And that's pretty simple - she is trying to sing her heart out, without complicated arrangements and epic stuff. And this is wise, you don't need the perfect pop song and the perfect instrumentation for the pitch-perfect voice. It would be like Whitney or Christina singing Carly Simon or John Williams (awkward).
When "19" was out, she was that cute songwriter with the jazzy voice and her guitar, singing about drama, daydreaming and chasing pavements (my favorite album, still). But since then, she has become an actual diva (but with a sense of humour). And it's again wise and smart that she co-writes her songs with Paul Epworth, Greg Kurstin, Tobias Jesso Jr or Bruno Mars, focusing mainly on her vocals. Just because if you chase two rabbits, you will not catch either one.
To the point now... It's the "21" sequel. The ballads are here ("Million years ago"), the pianos are here ("When We Were Young" ), the crazy vocals and the high notes are stronger than ever, while the drama has become sweeter and softer ("Send My Love (To Your New Lover)"). All the album producers, including Danger Mouse, have tried their best to build the songs around her ability to touch people's hearts and though every song has a different producer, the sound credit goes to Adele - it's all about her.
"25" is going to sell more than 3, maybe 4 million copies on its first week in the US alone. If you consider the fact that people don't buy physical copies anymore, this number in 2000 would have been 10 million copies and that's more than breaking a record. That's a proof of pure talent and poetic justice in music, in the arts, in the world. And, of course, it's back to basics. A for Adele (lame, but I had to)!