Seems cliche at this point to repeat the words: Silver Line isn't going to cut it.
I know this has been debated to death, but in general this is the area of the Silver Line that gets very good marks across the board by most people who have ever used it.
SS to Courthouse is one stop. Dedicated tunnel. Transportation vehicles every 8 minutes during rush hour. 2 minute ride. The Courthouse head hoses have this development surrounded, and I believe are to be integrated into the new development as well. For those who don't or can't manage the easy to most of us walk over the bridges, or when inclement weather precludes that walk. The SL will serve this area of the seaport just fine.
Pier Four and the Eastern half of Seaport Sq. will be served just fine by the WTC stop. The new massport apartments/hotel beyond the WTC will be served by the SL Way stop the same as Manulife, Park Lane, etc. already are. It's beyond that the SL starts to suck.
I walked it everyday for 8 years during all seasons. But, I'm not everyone. The bridges will need more winter attention in this area though with all the new tenants. The Summer Street bridge sidewalks are awful after any significant snowfall, and that is not just day of, but for days after they don't get touched by the city.
Congress and Moakley are going to start seeing a large increase in foot traffic, and will require similar attention. Northern Ave. as well.
Now that things are actually being built on the SL, it will start to show it is viable. It's not the best, but better than most make it out to be. That, and the insane ratio of parking spots to tenants/residents in the area being a thing of the past.
Until now, there hasn't been a huge demand or usage of it, because it hasn't made sense. If you work in fort point, you can walk from SS quicker than taking the bus across the channel, only to walk almost as far to your office. The only plus is missing the winter wind crossing the bridge, or driving rain on the same bridges. That and until recently you could park there for some of the cheapest prices in the city. $8 bucks when I started there in 2005. $17-19 bucks now I think. Getting much closer to the rest of the city.