I have never been entertained by someone's boasting, but I am always thrilled and happy to hear of a friend's accomplishment. e.g. I hate and get bored by long-winded stories about something where someone is basically only telling it to praise themselves, but I love to hear stuff from a friend who says "Guess what? It was my first time making my own curtains and they turned out well!" I love to hear stuff like that because it's part of my friend's life and she is genuinely happy about it, and I like it that she wants to share the info with me.
Basically, the closer the person is to me and the less long-winded the situation is, the more comfortable and happy I am with it. But I really don't have time for the people that praise themselves on a regular and ongoing basis... I really don't need to hear self-congratulatory stories each and every time I happen to see the person!
I also think the people that praise themselves on an ongoing basis are either way too overconfident to the point of arrogance, or they are insecure and always need the approval of others. I haven't met too many people who are in the 'happy medium' to praise themselves constantly.