Yeah King's Man is a pretty bad movie with good actors and some good stuff scattered throughout. First and foremost the movie as BG8 said has no idea what it wants to be. Starts out like a historical drama goes to spy thriller to farce to anti-war tragedy back to spy movie and then rushes to a weird action conclusion with a massively underwhelming villain.
Pacing is terrible. Way too much time devoted to the son wanting to go to war, and it's the least interesting part of the movie. They should have done that in the first 15 mins of the movie and committed to the silly Rasputin style stuff (a bizarre, but food scene) from then on.
The messaging in the movie is also bizarre and flip flops so often. Again, see the main villain whose motivations make zero sense.