”…Pinocchio is like a baby; it was a long wait for that first album and when it dropped, people were just happy that they finally had their own. Pink Tape is like a child, especially since the album as a whole showed some progression and growing up in terms of sound, all while keeping that bratty and feisty tone f(x) songs tend to have.

Thus, Red Light is the rebellious teenage years with the experimentation of sound that either hit the mark or missed it slightly. Fittingly, 4 Walls is like a young adult – f(x), while still facing uncertainty, are more confident in their identity.” 

- Seoulbeats: f(x) Matures In 4 Walls