Writing Perspective

My own strictly non scientific survey reveals only two 1st person in the stand alone stories and one serial. I feel that there is something not quite right about 1st person, though I don't understand what this is, just a slight sense of squeamishness.

There is a difference between true 'omniscient narrator' perspective and third person, in that usually a 3rd person narrative is from only one character's point of view.
This is how we experience the world, after all, through just one pair of eyes.
As others have said, one must be very careful about introducing another POV, because it jerks the reader out of the head of the protagonist. When this is at a chapter break or in the epistolary form it's most natural, but when the POV jumps about it's hard to follow.
I suppose that's why I almost exclusively write 3rd person.

I do a lot of first-person stuff, but I also have a tendency toward the omniscient. They say you should write what you know.

To me, 1st person always seems the most natural way to tell a story, just like an eye-witness account in a news report. After all, how does a third person know what happened if they weren't even there? I have occasionally come across a technical problem with it though. If you want your narrator to experience some sort of epiphany or revelation in the course of the story, they have to somehow conceal their new knowledge while they're telling the early part of the story. One way round this is to use a diary format, but that doesn't work if the action takes place in a short span of time.

However, it was only a couple of days ago that the most important advantage of 1st person occurred to me. If someone criticises your writing style, you simply point out that it's not your style, it's your narrator's style!

I find first person harder to write than third person. You need to describe the emotions and thoughts in a more complete way and make the chain of thoughts stick together and make sense. Third person you only have to describe what can be seen on the outside and it doesn't have to make complete sense, since you don't know the full spectrum of the emotions the characters have inside. But when reading a story, a first person story that is well written can grab me more intensely than a third person.

I'm comfortable writing in 1st or 3rd and reading in either. The one that is hard to do, and I've only done it twice here is 2nd person. The experience reading it, unless it's done well, can also be difficult.