I'm afraid your understanding of justice and my own differ greatly. It's probably an insurmountable impasse. To me, exposing a massive surveillance apparatus is a laudable act of heroism, and he doesn't deserve this kind of condemnation.
What if, just maybe, the laws you defend so adamantly are unjust? What about the consequences for all of us that live under them? Why not defend those that tell us the truth?
You can argue about whether they're unjust laws or not, but they still exist and if you break them, you should face the consequences. That's what the civil rights leaders in this country did, among others.
But honestly, from my reading, I'm mostly okay with what the NSA's doing and most of what he revealed isn't all that new or surprising (others reported on PRISM long ago, local governments have kept track of phone records for decades, it only makes sense the feds would as well). This is also what many citizens want their government to be doing, hence the many complaints about the Boston bombers not being adequately tracked beforehand.
The one part that troubles me is the storing of 'inadvertently' collected communications from US citizens for five years without a warrant. That seems wrong. Other than that, I only think there should be a bit more transparency. If Snowden's leaks lead to that, that's a good thing.