The Miami Times finds that a network that cost $5m to build still has spotty coverage: The contract was signed with IBM in 2006, and the network only recently came online. While it has municipal purposes, it's been pushed as a way for the public to get free Wi-Fi. The reporter wasn't impressed in his attempts to gain access.
The price tag is pretty high unless there were commensurate municipal purposes in which costs were conserved and service improved, and that doesn't appear to be the story the city is telling. The city's project manager says "16,500 people have signed up to use" the network, but as we've seen with other large-scale networks, it's never quite clear whether that's unique devices, sessions, etc. "Users" is often used broadly.
Finally, I missed the mayor of Miami Beach's badly researched comment back in October, reproduced here: "We are the first in the country to have a free citywide hotspot." Except neighbor St. Cloud, Florida, and Mountain View.