As a song, "Somebody" is very JYP -- it fits right in with the "Be My Baby"'s and even the "I Don't Need A Man"'s of the JYP catalogue. It's full of cliches in terms of melody and arrangement, yes, but what I really appreciate and adore about the whole package is the fact that it's also very youthful. I think of all the "retro" songs JYP has released lately, this is the song that best captures that playful, spunky but ever so slightly feisty sound that was perfected by Motown and the likes -- "Somebody" sounds like it could be a song for a big dance number in "Hairspray". "Be My Baby" was a happy song, yes, but it also had some weight and maturity to it, whereas "Somebody" is very light-hearted and vibrant, without being juvenile. It's a very polished song, with impeccable production and a tight, brave and urgent arrangement, but it's also very graceful and fun, with those "you-ooh-ooh-ooh"'s, those stunning middle 8 lines, all the way down to the hook itself.
But what drove the point home for me was ultimately that "Somebody" isn't just a beautiful song in theory, it's also gorgeous in practice. The first version that I heard was the live one, and to have two singers who can deliver the main point of the song on stage as well as they do in recording really does make a difference. Ji Min's voice is very smooth, very clean but also very practiced so she has the technique to make that smoothness interesting, and Yerin has this gorgeous timbre which is also coupled with the technique to deliver things like that high note of hers at the end. Their voices also work extremely well with each other -- as much as they balance each other out in terms of timbre and tone, they're of equal skill set and technique. No one has to carry someone else's weight, and that really makes a difference.
What really makes "Somebody" stand out is the fact that JYP took advantage of the fact that 15& is basically made up of two, stunning voices. For me, the main selling point of the song is the fact that this is a song that proves what a huge difference talent really makes in pop songs. That, at the end of the day, a good song sung by a phenomenal voice is lightyears better than a good song sung by a mediocre one, no matter how much the song hides mediocrity. Instead of having to cover up for insufficiencies in execution, "Somebody" can just go and make itself nice and pretty -- you can have those parts like that double bridge at the end and the belting-fest, because these girls can pull it off.
Ji Min and Yerin can do more than pull "Somebody" off, and because of that, what is a dynamic and youthful but tasteful and polished song gets one extra quality -- effortlessness. At the end of it all, it's that effortlessness that drives all the other qualities of the song and so for that to be perfected gives way to a myriad of other, amazing, qualities that the "Somebody" brings to the table.