I am a tech worker raising my family in Brooklyn and it's quite lovely. Expensive, yes, but lovely. Whether you find it a "rat race" of a lifestyle or not is much more dependent on your internal psychology than the city itself.
Serious answer: Yes, the landmass that constitutes Brooklyn is large. The landscape of the main neighborhoods that have gentrified over the years are not so big. If you actually live there you know which parts I am talking about.
What are you talking about? By area, Brooklyn is more gentrified than not-gentrified.