I chose this drama expecting absolutely nothing except the pleasure of admiring Park Hae Jin. I now believe it was the best approach, since I got what I wanted and more.

The plot is quite ingenious, even when almost all the situations these characters are thrown into range from slightly unbelievable to surreal, all spiced up with action and laughter. I don't think the drama ever intended to be taken seriously, and if you keep this in mind, you'll enjoy the whole show very much.

Let's get rid of its faults quickly, then. No matter what country they are in, everyone speaks English. Korean seem to live under the impression that the whole of Europe were a substation of the States, where, say, Russian people speak English among each other, prisoners wear orange in Hungary, and French eat cereals for breakfast. Ingenuities like these are scattered throughout the whole drama, but as I said, to fully enjoy Man to Man one needs to overlook the incongruities and stay focused on the characters and their antics.

In fact, the characters are all likable, even the villains. There's an ever-present light undertone to the drama which I personally found charming. No trace of melodrama is to be found, so that you can watch with due expectations but without having your heart shatter in a thousand pieces at every turn or boiling for anger at the injustice of life.
Park Hae Jin is a sight to behold. He's believable and engaging in the action scenes, kind of goofy in the romantic ones, clever and quick-thinking in his job and invariably gorgeous looking in his sleek costumes and generally suave style. Therefore, if you watch M2M for the sake of him, you won't be disappointed.
I loved the female heroine too. I'd read critical comments about her being annoying and inconsistent, but I honestly agree with none of them. I even liked her hairstyle: it makes her look younger and more breezy than she actually is, but it all adds to the inevitability of K falling for her and not for any of the stylish, fashionable women he meets for his assignments.
The love story between these two is sweet, but has to be taken as a side plot, not the core of the story. If you want to be swept away by a sizzling passion, look elsewhere. I was happy with this too.
The Hallyu Star made me laugh from start to finish and the same goes with all the secret agents whose actions are so conspicuous I had to laugh hard at their preoccupation with undercover and secrecy.

The music is kind of atrocious and badly edited, at times too loud and most of the time unnecessary. Some pieces got a smile out of me, which is the best I can say about this soundtrack.

Since this story does not rely too much on high voltage suspense, it can be re-watched again and again without losing its charm.