When I first submitted my manuscript for Genetic Attraction to Loose Id, I got a revise and resubmit letter that suggested that I needed to work on point-of-view.  Now, I’m new to fiction writing (although I’ve been a non-fiction writer for a lifetime), but I thought I knew about POV. I looked at my manuscript closely. I wasn’t head-hopping (jumping from one character’s point-of-view to another’s  a number of times in a scene). I always clearly indicated switches in POV.  What was the matter? I expressed my frustration to my editor who tried to help, but I just wasn’t getting it.
After weeks of bad trial and error, my editor sent me a document from a workshop that talked about deep point-of-view. (DPOV). I read it and the lights came on. It was the “wa-wa” experience (remember in the Miracle Worker when Helen finally connects the feel of water on her hand to the symbol for water Annie was making?) Suddenly, I understood the difference between skating lightly on a character’s viewpoint, and being locked into his or her thoughts and feelings, and that understanding literally transformed my writing on the spot. I got the difference between:
Omniscient POV– -It was a dark and stormy night.
Shallow POV –John saw it was a dark and stormy night.
Deep POV – John pushed against the door, fighting the intense wind that tried to slam it on him. He held up his hand in front of his face, but his eyes just couldn’t adjust to the darkness. Crap, he didn’t know it could get this dark. He hated the blackness. He couldn’t stand the sense of isolation. 
I understood that point-of-view wasn’t a thing that made writing good, it was in many ways, everything. It is the key to the reader’s emotional involvement and satisfaction. A reader doesn’t know necessarily why they feel unconnected with a book or scene in a novel, but, chances are, it’s because the writer has missed deep POV. Some pretty famous authors who are notorious for head-hopping likely get away with it because, while they are in a character’s head, they are in DPOV.
Since that first moment of understanding, I’ve gone on to workshops and readings in an effort to make my point-of-view expression deeper and more natural. While I went through my first two books line by line to edit the POV, I find that today I more automatically write in DPOV, and when I don’t, I catch myself more quickly.  I’m still a newbie and have much to learn, but I’ll be forever grateful to my editor s for that guidance. Now, if they could just improve my commas! 
As a reader, do you notice point-of-view? Does it ever intrude on your reading experience?