It's the same appeal as any location information, basically. Except I think Tampa fucking rocks. ;)
Mostly, it's incredibly different from other settings (especially Seattle).
On to some of the details I'd like to discuss.
The difference in the underworld in Tampa provides a lot of the changes that really interest me in the locale. One, you've got a city that has a great deal of influence from one particular syndicate. This same syndicate takes on a bit more of a historical style than seen in most of the canon SR material. With the break up of the US, the shattering of national lines and economies, and just the general fucked over nature of North America...the underworld in North America has to see some major changes. The idea of a combined cross-national syndicate (as seen with the Mafia through much of the 20th century, up until about 1970/1980) has to come crashing down, and that has a big effect on how the Guidos play out in a given locale. The Commission isn't going anywhere, obviously. But the idea of alliances spanning the whole nation, jet-setting mobsters working on rackets in multiple cities, and nigh-impenetrable secret organizations quickly starts to fall apart in the 2070's. You have prisons and law enforcement handled by an extraterritorial corp that can remove the gloves and operate outside the law if necessary. You've got an extremely high level of surveillance in general society, and a global and instantly accessible information network. So, this is going to focus the Mob into loosely allied factions that are focused primarily on each individual city/region. This begins to take you back to the kind of setup the American Mafia faced prior to the rise of Luciano and his cohorts. Only this time, you don't have the rise of Prohibition to provide a quick upsurge of power for the Guidos.
How does this relate to Tampa? Look at Santo Trafficante (Sr, but particularly Jr). He's one of the mobsters that best exemplifies what Luciano's changes brought to the Mob. He organized rackets that spanned the nation and the Carribean. Along with folks like Meyer Lansky, Don Marcello of New Orleans, and Luciano; he worked heavily on making the French Connection and Golden Triangle narcotic trade easily accessible to North America. This group led a huge drive to bring money and rackets to Cuba and other Carribean nations, while also creating narcotic and gambling rackets that spanned much of the US (the birth of Las Vegas, the rise of the near statewide bolita rackets in many of the Southern states, the numbers and policy groups of New York/Boston/Philly/Jersey, etc.) But with the changes in SR, Tampa finds itself in a unique situation. This isn't the Tampa when Trafficante was at the height of his power. This isn't the Tampa that birthed a Mafia Don who may very well have been involved in the death of the US version of King Arthur and Camelot. This is the Tampa that is facing up to massive problems, and has been beat down. This city has held an entrenched Mob group that has been battered steadily lower over the intervening decades. So instead, you're looking at a city that is wide open for the rise of another Trafficante. You get to play around in a setting which may be facing the birth of a new leader in the underworld, the kind of leader that will lead to recreating the level of power seen in the "ancient" past. To me, that's part of the excitement and potential found in Tampa.
Now, start to toss in the influence of the South American cartels ("ghost" cartels my ass...) and the potential only increases. Tampa lends itself to the style of SR that I think a lot of this group prefers. Leave the Day-Glo mohawk punk rockers over in Seattle. Freaks are going to be freaks in this region of the world. You have a city that doesn't have the stigma of being the home of shadowrunner culture. None of the silly "Shadowrun" reality shows, "professional" criminals who couldn't even spell pro let alone professional, and a strong mix of organized crime that actually reflects the reality of OC in North American and not some kind of gamer geek pipe dream. Okay, so I'm biased. But I think I got some of the points across. Feel free to poke holes if you like.