Me and myselves

Point Of View, or our dear old POV, is a question all writers must face sooner or later. Usually sooner. In simplistic terms, POV answers the question "who tells the story?" and there are four major groupings:

1) first person - ex. I got hit by a train and I could feel my ribs break.
2) second person - ex. You got hit by a train and must have felt your ribs break.
3a) third person limited - ex. She got hit by a train and could feel her ribs break.
3b) third person omniscient (all knowing) - ex. She got hit by a train and must have felt her ribs break.

Talking about POV is the same thing as dicussing the story's narrator.

1) In 1st person, the narrator is the same as the main character. It's all seen from her or his head and the story is told completely influenced by this character's values, prejudices, dislikes, likes and experiences. The reader will not know anything beyond what the character knows, which makes some plots trickier to handle. In my current WIP I balance first person with short scenes in omniscient 3rd person so to introduce the threat to the clueless main character. According to some the problem with first person is that the story easily gets "ranty" - the writer need to note the train of thought chronologically and "the way it's thought". I haven't edited my way through enough 1st person narrations to judge on my own if this statement has any truth, but it's good to bear in mind.

The challenge - you can't present information unknown to the main character
The opportunity - you can give your readers an intense ride and tie them closely and emotionally to the main character

Ex.
I got hit by a train at 5.14 pm and felt my ribs break. Not a pleasant feeling and my rage at the hand which had pressed against my back grew and engulfed the pain. I would get the son of a bitch. One way or the other.

2) In 2d person, the narrator is not the same as the main character. The main character is the "you" in the story. It's the story about someone told to that very person. I've seen this done spectacularly well in one book - Robson. The story is about a woman retelling the story of her husband's (the "you") struggle against cancer. I can imagine it would work great in books about alzheimer as well, or senile characters (for example "The Notebook", although they don't use that narration technique in it).

The challenge - to connect with the reader when the story is obviously told to someone else (unless the reader can identify with the "you" in the story)
The opportunity - in my mind, you can tell difficult tales in a little less personal way and therefore handle less cute subjects.

Ex.
You got hit by a train at 5.14 pm and you must have felt your ribs break; the paramedics said you were still conscious at the site. It can't have been a pleasant feeling, but perhaps your rage against the hand that had pushed you out on the tracks engulfed even your pain. You wanted revenge, and you would get in one way or the other.

3a) In 3rd person limited, the narrator is the main character, although not in as a direct way as 1st person. However, you as a writer must still obey to the fact that everything is limited to the character's experiences, intellect etc. You can relate direct thoughts just as you can in 1st person. The technique allows you to have multiple characters/POVs, but for all that's holy, NEVER change POV in the middle of a scene! I don't care which author has done it or which smart person tells you it's possible. You say you have a good example? I bet it's in 3rd person omniscient and isn't a POV change at all, just the narrator focusing on another character. There's a difference.

The challenge - to keep the view limited to only one narrator within each scene
The opportunity - to invite the reader to share the mind and experiences of the character yet be free to step out of the emotional rollercoaster at times.

Ex.
She got hit by a train at 5.14 pm and she felt her ribs break. It wasn't a pleasant feeling and her rage at the hand which had pressed against her back grew and engulfed the pain. She would get the son of a bitch. One way or the other.

3b) In 3rd person omniscient, the narrator is a completely other person than the main character and who knows everything (or pretty much) about the characters and perhaps even the story. If the story somewhere contains "little did she know" then you got an omniscient narration. The narrator can imbue the story with prejudices, knowledge and "memories" that the main character (or character in focus) doesn't know about or doesn't share. The narrator has a distinct voice and there are no direct thoughts from the characters (direct thought = 'This sucks'; wheras indirect thought = 'This sucks, she thought').

The challenge - it's not possible to relate the characters feelings and thoughts directly
The opportunity - memories, knowledge and other facts can be freely related by the narrator regardless of what the character/s/ wouldn't know.

Ex.
She got hit by a train at 5.14 pm and she must have felt her ribs break, even though she never could recall that moment. The man that had pushed her out on the tracks was already gone by the time the paramedics turned up. The train guard, who had been tending his inflamed tooth when the so-called accident happened, said she had jumped. He was afraid to admit anything else, even to himself. The paramedics believed him; everyone did. But she knew the truth. She would get the son of a bitch, she thought, one way or the other.

Feel free to discuss these points in the comment section, or post your own examples (or paragraphs you wonder about). I'll do my best to give sensible answers. I'm also very curious about which pro's and con's you have experiences with each narration style! Please share.