For one, I'm somewhat surprised that there were people that didn't know of the existence of something like this program. I thought it was rather common knowledge. How else did people think that the government prevented various convenient online/digital services from being used to successfully conduct crimes and terrorism?
Anyways, the issue with Edward Snowden is not that he informed the world about this secret program, which one could guess exists without being told. Although, his informing the world of it does decrease the program's effectiveness drastically, as it was one of those things that works best when no one knows about it. I'm still wondering why people are fine with a corporation knowing their information, but not the government.
The issue here is that he released information that he was legally obligated to never reveal. Only in the most situational or extreme of cases will a person be able to get away with doing that, as keeping confidential information secret is extremely important.
As an ending thing to mention:
Many people seem offended that the government has this secret program. However, as far as I know of, not one of them has proposed an alternative that is less invasive, just as or more effective, while still causing no harm to the law abiding folk.