I do think Assange's work is crucial in our times. After the high profile wikileaks stories hitting the global media, the loopholes in our international reporting were closed. He has made several good points about how the nature of the press is changing for the worst, and that freedom of speech and press are on the decline due to globalized and powerful influences.
Manning betrayed the army and for that he should be punished, but I do respect that his betrayal was due to moral conflict and not a sincere wish to harm his country. His heart was in the right place even though his loyalty should have already been procured.
As for the Nobel Prize... it lost all credibility when it gave Obama the Peace Prize. Obama has done nothing for peace. He has perpetuated the policies of all administrations before him, and has prolonged wars on multiple fronts that have damaged our economy and reputation. His foreign policy is no better. He's a shill just like any other President.
I think of Wangari Maathai who won the peace prize for her tree planting campaign in Kenya that changed the political landscape of her entire country, and then I look at Obama and just shake my head. I don't even know how most politicians could even qualify for something from the Nobel committee, let alone Obama.