Let's first analyze the word Traitor.
A traitor is one who commits treason.
"The offense of attempting by overt acts to overthrow the government of the state to which the offender owes allegiance or to kill or personally injure the sovereign or the sovereign's family."
-Merriam-Webster Dictionary
Is Snowden's intention to overthrow the government of US? Probably not, but can you make a case that this is an act that aids to treason. Probably because it does make the government look bad. Yet, you could argue that by exposing the wrongs of a government, Snowden is trying to correct the government.
So if you go with a literal meaning of Treason, you could argue that Snowden is a traitor, but you could also point out that he is not a traitor.
Now, let's look at it from a different angle, and that's where it gets more complicated. A US citizen has to pledge allegiance to its flag and the one nation republic. The flag symbolizes the country but a country is an abstract term; what does being loyal to a country mean? Being loyal to its Government or being loyal to the Constitution? This is one important difference and Snowden being a traitor or not lies on this important choice.
If you say, Snowden betrayed his government, then yes, he is a traitor. But shouldn't the government follow a set of rule that is known as Constitution and protect it's bill of rights?
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
4th-Amendment, United States Constitution.
So, the Government sort-of violated the 4th amendment and Snowden exposed this violation. Even the Patriot act doesn't allow this as monitoring (falls under unwarranted search) is done for the entire population, not a suspected terrorist.
So, I doubt I would call him a traitor. But is he a Hero? I will need more information about his history and his motives before I call him a hero. As for him going to China, I think that's one country that can protect him and that's why he chose that. But again, we need more information on him before we can argue for him or against him.