Martial arts scenes in action films have been one of the biggest promoters of martial arts as well as one of it's biggest detriments as it promotes romanticized, hyper-realistic views of fighting. But this is nothing new as stage combat has been a part of dramatic action since the beginning of theater.
For the layman it's a junk food fantasy seeing a single man dispatch numerous enemies and escaping with only fashionably placed brusies. For the martial artist it can be a ego trip or it can be a cringing moment watching realistic techniques compromised for the sake of dramatic effect.
So much goes into the choreography of a fight scene. There is not a single frame that goes into fight choreography that is not planned. There is no Stanislavsky "method acting" in stage combat. People will get hurt and productions will get shut down.
A good screen combat scene involves the following:
1) Good story. First and foremost the purpose of a fight scene (or any scene) is to further the plot of the story. Period.
2) Good STORY.
3) Character development. The fighting method should reveal more about the character. Particularly the character's background and especially his or her state of mind at the time of the fight. The actor's acting should go beyond just "grimacing", "grunting" and looking cool on camera. He or she should be revealing more about the character's emotional journey.
4) Pacing. The pacing should reflect the overall tone, atmosphere and speed of the film. This is determined by the director and the editor. Not the martial arts choreographer. It's his job to help the director tell the story he is envisioning.
There are other elements of course too which add to theatrical combat such as: Sound FX, music, lighting, cinematography and in some cases Visual FX. But the aim of course is suspend the audiences belief and make all these elements appear seamless.
A good case to point out is Guy Ritchie's Sherlock Holmes and the sequel Sherlock Holmes: Game of Shadows.
Guy Ritchie in addition to being a filmmaker is also an accomplished martial artist in Shotokan Karate, Judo and Brazilian Ju-jitsu. Ritchie presented the perfect balance of the nuances the techniques (which martial artists would appreciate) while not sacrificing the obvious fantasy and escapism of story.
Though it wasn't said, it was obvious to any Wing Chun Kung Fu practitioner that Sherlock Holmes (the worldly, eccentric, calculating man that he is) was using Wing Chun in the film's combat scenes. The key words here are "worldly and eccentric". This is a good example of character exposition: "What kind of Englishman in 1891 would study Chinese martial arts? Why?? And what kind would he practice?"
As 19th century Westerners laughed at what they called "Chinese Boxing" (and the Boxer Rebellion only right around the corner in 1898) Sherlock Holmes is likely they kind of person who would want to learn more about it --- especially because others are laughing at something they don't understand and know very little about.
Of all the Chinese martial arts, Wing Chun is one of the most logical, straightforward but deceptively direct of all the Kung Fu systems. How could Sherlock Holmes resist not adding this combat art form to his repertoire? How could he resist the challenge of being a foreigner and infiltrating closed or secret societies so he could learn it?
Robert Downey, Jr. is a practitioner of Traditional Wing Chun as is his instructor and fight choreographer Sifu Eric Oram.
Would it be believable for Sherlock Holmes to stand in a perfect Wing Chun ready "combat stance" in the film? No. Would it be believable for Holmes to use certain elements and principles of Wing Chun in his own modified but effective way for his means? Yes. And this is good character development and ultimately makes a good theatrical combat sequence which HELPS develop and give perspective to the story.
Guy Ritchie understood this well as there are slight differences in the blueprint choreography given to him by Sifu Eric Oram and the other fight/ stunt choreographers. Below are two clips from "Stunt Schooled: Sherlock Holmes" featuring the choreography planned intercut with what was finally shot and edited for film.