Yeah, not sure what he means by big box. Ironically,
@superjohn it reminds me of parts of Chicago, and yes it has changed dramatically in the last 2-3 years. It's certainly modern and includes lots of chain restaurants (but not all and most are local chains) from the World Trade north-west until you hit the brick buildings of the leather district. That's because none of it existed even 5-6 years ago except for the Moakley courthouse (and it's still pretty new). So yes, it is lacking in traditional character. South-east of the World Trade you've got an excellent concert venue, Harpoon brewery, some genuine commercial fishing piers, the cruise terminal, a cargo container port and then Castle Island. It's a bit more gritty and authentic. The leather district has character though. Lucky's Lounge is still there, a blues and jazz club that opened when I lived in Southie, so around 2001. It was the only thing there at the time.
Seaport is just branding. The whole area is "Southie" with whatever connotations that carries for people.