I no longer live in Miami but it will always be home. For the 10-plus years I did live there, it was never really considered a gastronomic hot spot. Of course you could get great food; a lot of Cuban cuisine, seasonal stone crab, Nuevo Latino, and lovely seafood, to name a few. You could also find a lot of farmer's markets during the cooler months and there was even a CSA (community shared agriculture) distributing fresh produce from the Redlands - but it never really had that food-town feeling that places like New York, London, Hong Kong, or Paris have, for example.
This was true until very recently. In this article from the New York Times, Frank Bruni details some of Miami's best dining options available right now.
Although I am a little jealous that all this happened right after I left, I can say that a lot of it began while I was still there. Local chefs like Michelle Bernstein (my ex-boss at the Mandarin Oriental's Azul) continue to gain popularity along with talent like Michael Schwartz and several others. These names draw attention to Miami in a great way and bring the city closer to recognized food-town status.
I'm excited for my Miami and I hope to visit soon and eat my way around town...