"ore" is used especially among young people. However, it is sometimes used to adults for friendly conversations. "ore" is never used in formal occasions. For men, "watashi", "watakushi", or "boku" is used. It seems people older than 40 or 45 years old are more likely to use "boku" when addressing themselves, although young ones tend to use "watashi" or "watakushi."
(I don't really know why...but most people I've met talk this way.)