I was there for 2 weeks in 2015. It's fine for the most part. You do have you keep your eye out for pickpockets, though.
I took the Metro all over the city and never had any problems, but my coworker did stop a purse snatching on the metro. Just as the doors were closing this guy grabbed a woman's purse and tried to jump out. But my friend grabbed the purse too and he was a lot bigger than the thief. Thief let go.
Oh, and don't just leave your cell phone sitting out unattended on the table when you're out. Apparently that's a good way to lose it.
Other than that, I walked all over the place buy myself and felt safe.