Taeyeon continuing to make what seems to be music she actually wants to create for her solo career (as opposed to the bubblegum hits when she was the leader of SNSD). Vocal effects at the beginning are very Imogen Heap-y, but the song settles into a groovy R&B song with a very nice bassline, and her vocals sound great during the bridge.

https://youtu.be/im1UUY8dQIk

I'd love for her to make some more R&B-styled songs like "Sweet Love" (https://youtu.be/YHGA_yVAeB0) or "Lonely Night" (https://youtu.be/yLeZ0ZH9dIU) from her debut solo album last year, but this is good too.