I was using Yahoo Buzz for several years - successfully however NOW Yahoo Buzz is dead since several weeks already CLOSED - if you go to your YBuzz account it redirects to www.yahoo.com and to my knowledge this YBuzz end was done without any official announcement to registered YBuzz users hence it is useless to further argue if good or not, YBuzz is www history just like another yahoo operated blog site is closed and a yahoo owned bookmark site sold (delicious) this month.
Yahoo buzz just help to improve traffic to the website. It is nofollow and it is not useful for the improvement of the keyword ranking.
Yahoo buzz closed and down since weeks, thus it makes no sense to further elaborate on on value or sense of something that is past of www history. Yahoo closed and sold a few services in past weeks/months. They may have their obvious reasons or needs to to so.