I love to use them, but I have been undergoing therapy to get over my addiction. I use them for trailing thoughts, pauses, and to indicate dramatic vocal inflections. I was always taught that three dots, with spaces between, were used in the middle of sentences, and four dots at the end. Three dots and one period, basically. I see that method used in many printed books.
After I started writing fan fiction, I ebgan getting lots of criticism for ellipses usage. Some people wanted them spaced, not spaced, used, not used, three dots, four dots, or only used at the ends of sentences. I found that no matter hwo i used them there was always someone who thought it was wrong. So I just imitate what I see in printed books.
If it works for Scribner, Plume, Penguin, etc. then it works for me.