I don't mind some of the whistle blowing WikiLeaks has done, notably the Afghanistan video and financial crisis correspondence. Many feel the diplomatic leaks of 2010 played an important role in the arab spring uprisings.
Of course there are significant negative effects from the release of classified military documentation as well as US' diplomatic documents, which weakens the US diplomatically and even worse, puts American servicemen's lives at greater risk.
For this reason Manning is in jail and Assange is wanted. Completely fair imo.