"Blue", although still completely Big Bang, is very different from almost all of the material we got from Big Bang in the past. Prior to this they were pretty much zipping through poles -- very intense uptempos or very sensual (for lack of a better term) R&B midtempos, rock-inspired numbers, or synth-heavy ones. "Blue" is right smack in the middle of all of that. There are a lot of things it's not, for starters it's an almost complete deviation from the fun, "let's run around stage" Big Bang we all know. For Big Bang standards, it's as if they sucked all the life out, but for regular standards that's still pretty good!
Basically my point is that Big Bang are maturing. Not in the superficial jump from album to album with the token "let's try this", but that turning point that encompasses the entire concept of Big Bang, from the material to the marketing, and even to the fans. If you think about it, Big Bang have been around for six years already. Six years! That's a century in idol years! (regardless of what country you're in) If their fans were thirteen or fourteen when they started out, in middle school/early high school, by now those fans would've already gotten into university or even started working. Even if you say that they constantly gain new, younger, fans, the majority of the Big Bang fans are already in their early 20's, and have much more mature tastes. They have to cater to those mature tastes, or at least start on it.
"Blue" is exactly like that. If someone were to play this in a mall or a public place at regular volume no one would really notice it, and this morning I was listening to it in school and just on my laptop speakers, and honestly I was bored to death. I knew it was a pretty song, but that was about it. It was only when I came home and listened to it with headphones, really concentrated, and listened with the mindset of reviewing it, did everything else come out.
A possible technical justification of this is that yes, the vocals are on top of the entire track, and that's essentially what you hear in pop songs (what's called an "ad(vertisement) mix"), but the thing is, the melody is secondary. The intensity, and beauty, of the song comes in the way the melody, the rap, and the instruments all fuse together and deliver the entire song. The sung verses are very gentle, and if you're not thinking hard enough they can be mistaken for emotionless, but listen to what's behind them -- those almost flute-like synths, the raw but graceful "acoustic"/non-electric guitar whose line matches the bass -- there's so much happening. You have to listen to everything, but you also have to listen to the individual elements then relate them all to the whole, and that requires some kind, any kind, of critical thinking.
Which brings us back to my water analogy -- when you're thirsty, you think about what water will do to your body as a whole, but you also concentrate on the fact that it's refreshing and it actually tastes like something when you're thirsty. "Blue" has dimension, it has kick and it has dynamics, but you not only have to be in the right frame of mind to be able to hear those, you also have to be very critical. If you're not, it's just another mellow song, and in a sense it isn't that enjoyable. It's in that intellectual angle that I'm convinced that Big Bang are indeed maturing.
Just a side note, but I guess "Blue" emphasizes a point I always try to make -- that K-Pop isn't entirely stupid. The simple fact that there are people like me who write about K-Pop and take it seriously should be enough to prove that, but apparently it's not. K-Pop isn't stupid, and fans are not brainless. Whether it be in news, reviews, or even the music itself -- they all have to be produced with that mindset, because it's true. News writers think their readers are stupid, so they feed them with useless news, there are critics who think their readers are stupid as well, so they themselves stop thinking critically, and talent agencies along with the production staff think fans can't think for themselves, so they try to get away with putting out bad material. News flash people, you're the reason why the fans seem to have lost their brains, but you can also be the reason they start thinking critically.