Can't make my mind up on this. Is he a whistleblower being treated unfairly or a malicious hacker who deserves to face trial?

BBC video: 'Assange smeared faeces in our embassy' "Ecuadorian President Lenin Moreno tells the BBC why his government revoked Julian Assange's asylum."

Had mental instability set in (assuming he was mentally stable to start with)?

The "trollexposure" blogger quoted elsewhere on this forum has also written about Assange:
Out of hiding and into a van

I keep going back to the fact that Assange appears to have a rather ruthless and callous streak ("David Leigh and Luke Harding's history of WikiLeaks describes how journalists took Assange to Moro's, a classy Spanish restaurant in central London. A reporter worried that Assange would risk killing Afghans who had co-operated with American forces if he put US secrets online without taking the basic precaution of removing their names. "Well, they're informants," Assange replied. "So, if they get killed, they've got it coming to them. They deserve it." source) and Wikileaks seems only to have leaked information exposing Western governments, while collaborating with Russia (e.g. on the Democratic party leaks, while Assange also had his own show on Russia Today), so can't really be seen as impartial.