I am not by any means an expert on drafting mission statements, but in most cases I think shorter is better.
To help get the discussion started, I'll lift an excerpt from the opening paragraph of the Article submission guidelines document:
I think one important element of the JCM that the above statement misses is that we are actively seeking community participation, and I think that should be captured in our mission statement.The Joomla! Community Magazine provides resources, reviews, news and opinion on the Joomla! world, with an emphasis on all of the positive things happening in the Joomla! project and its community.
What thoughts, ideas, questions, and suggestions do you have to help us create a JCM mission statement?