I spent 2 years living in Miami. It's certainly different to the UK. Very hot and humid weather 6 months of the year (yes, it can get too much !) it's definately not cheap, especially for food shopping and almost seems cheaper to eat out. Miami is an extension of Cuba, not a bad thing, but be prepared to speak to lots of people who can't speak english, only spanish.It's expensive for renting and has some very run down areas, so your choice tends to be limited to South Beach, Brickle etc, all expensive areas (+$1000 per month for a small apartment)Orlando would definately be cheaper for renting purposes.
That all sounds very negative, but really it's quite a wonderful place too, colourful, vibrant, busy, and some very nice areas, plus its not far from the Keys, a personal favourite. I still have family there and tend to find myself heading down there for the weekend at least once a month as an extension to work duties in New York but would I move back.......probably not. South Floridians don't have any road manners
Hope that helps !