At some point, nice is subjective. And Mission definitely has some sketch spots. But Castro, Eureka, Noe border it and are even nicer; then there's Hayes and the Haight and Alamo Square; head west on Haight and you get to Cole Valley and the Inner Sunset; north of Haight you'd hit a few patchy blocks on Fillmore but then come to Japantown, Pac Heights, the Marina. And that list is not even close to exhaustive: the point is that there are large contiguous areas that are nice, walkable, and safe.

It's much nicer than soma in my opinion and there are basically only two drug dealing/prostitution corridors along shotwell area and capp.