I think that it really depends what he revealed, there might be more secrets he gave away to our enemies.
However, if all he revealed was that the US is spying on its own citizens, then I think he is a hero.
I think that each spying instance should require a warrant. the government should not be allowed to do whatever it wants if it is illegal.
All (as far as I know) Snowden did was to reveal that NSA is doing illegal stuff.