Whether it's first-person or limited-third, I've always preferred a story that keeps its narrators to a minimum. One is perfect, two can work well, whether its two protagonists with different viewpoints or protag and antag, just to give us readers some variety.

Personally, I don't think I could write more than two main POVs in a single story - I'd start getting confused.

When reading too many POVs, I also suffer from inability to relate, or, even worse, the characters start sounding like each other, and as far as I'm concerned, this is a cardinal sin as an author. If you're creating different characters, the stipulation is that they are fucking different. Too many POVs, and the voices all blend into each other.

 

I liked ASoIAF a lot, and I think the reason why the multiple perspectives work so well is that it's not a story about any one character. It's a story about a whole world, so multiple points of view work well. I felt that Martin put the story first, then chose the best way to tell it, not the other way around. I only got irritated with the last book of the series where he split up the viewpoints and basically told the same piece of the story twice. I certainly wasn't annoyed with reading about the characters (many of which I like or find interesting), but I was annoyed as hell because the story wasn't moving.

Another book I've liked recently is American Gods by Neil Gaiman. The main story is told through single character, but some of the background is told from other perspectives. I think the reason why he gets away with it is that he keeps the different pow chapters short, they are set either way back in history or far away geographically, and by the time he rolls out the first one the main character is already well established. Also the chapters have something of a dreamlike quality, and read almost like dream sequences.