Generally negative but it's a very complicated issue that just "positive" or "negative" don't really fit.
Yeah, should have included that neutral option. That seems to be the right answer here. Obviously the plight of the people who have lived in these neighborhoods should be taken into account, but people should be free to move wherever they want. Especially if it is done for convenience, such as living close to work, I don't see how one can criticize it. Of course those who work in Silicon Valley, but commute by train from SF everyday are a group that could be criticized.