The location the Boston group has proposed for Amazon is the Suffolk Downs race track site on the East Boston - Revere town line. Perhaps with all the Amazon building the area would improve, but the place feels like a wasteland right now.
It's on the other side of Logan airport so there's a lot of airport service infrastructure around. There is a huge field of fuel tanks, big box stores and highways. It's also very cut-off from the city proper. There's no way to get to downtown Boston without going through the harbor tunnel and dealing with the associated airport traffic.
If might be interesting if they could build some sort of bridge directly over the Chelsea River into Chelsea.