There are a few negative things as overhang from the rest of government (requirement for citizenship: so many of the great people I know are non citizens, even if many have green cards; drug testing, which doesn't really serve a meaningful purpose), but those are the reality, and don't diminish the value of the program in any way.
I would strongly recommend looking into USDS to anyone who who wants to make a difference in tech. It is a great place to go in the middle of a longer career at a post IPO company like Google/FB, or are between projects.