I lived in Atlanta for 5 years, and live in Sedona, AZ for the past 2 years. I sometimes visit Phoenix.
Phoenix is not where I want to live. The tech scene is kinda anemic -- and granted, I'm used to Atlanta and Seattle.
Traffic isn't bad all the time, just the times when you want to go anywhere. Much of the city doesn't have good drainage, kinda poetic that the flow of traffic in Phoenix resembles the flooding that happens during monsoon season.
Like Atlanta, in Phoenix, you need a car. Unlike Atlanta, in Phoenix you also need A/C. It offends my sensibilities to see so much swimming pools and even an indoor ice rink in the middle of a desert. I don't generally like how the city is laid out, overbuilt, and I don't like the overall culture. (Though there are some really neat places here and there).