"Falling for Her Secret Side" is a weird choice of a title for this manga, given that her "secret side" is explicitly not the side that he falls for. But oh well. While I have consumed a lot of media that are overall far worse than this one, this is literally the only media I can think of that makes practically 0 use of its own premise. 99% of the workplace can just be removed and the story is practically the same. The only thing it manages to establish is that our two main characters are so ludicrously unperceptive that they fail to recognize the personclosest to them simply because they put glasses on or took them off! And this in turn breaks immersion and damages my interest in the manga as a whole, because it's hard to take this seriously as a supposedly down to earth slice of life story when we need to accept that putting on a pair of glasses is the ultimate disguise. Why not just keep this story at school?

This is a very, *VERY* bland romance. 43 chapters and barely anything interesting happens. I don't mean just plot-wise; things just do not happen. The overwhelming majority of time is spent on the two main leads making incremental progress in their relationship. But because the characters are so shallow and undeveloped, that by itself is boring and uninteresting. Both of these characters barely have a personality, so there's nothing of interest in just watching them interact.

So, what makes the characters shallow and undeveloped?
- The guy character is a generically nice guy who loves books... and that's it. That's his whole character. And these are the only two traits he needs to make his way into the main girl's heart.
- The girl character falls under the unfortunately common romance trope of "girl who is outrageously desirable in-universe and yet practically no one ever tries to get close to her". It's a common technique used to create a love interest that is both incredibly desirable and yet barely interacts with any guy besides the protagonist. This is part of why she feels less like an actual person and more like some idealized figure that exists for the protagonist's sake. At least later in the story she does get a little bit of background characterization, unlike the protagonist. But it's not nearly enough.

Moving on: what are some positives?
- The art is appealing enough.
- The pacing is... well, not good, but decent.
- The protagonist's best friend character is actually a positive contributor. Not only he helps the plot speed up from snail pace, but he has his own sideplot which is left hanging in the background to provide a degree of interest and then is dealt with by the end.

Final verdict?
This is a boring, bland manga that is bad in an inoffensive way. There is nothing particularly interesting, exciting, or noteworthy here. Just some common & lame romance tropes. Even for people who specifically like romance, I would recommend trying to find one that actually does... something.