You can get there by train from
Prudential Station on Huntington Avenue (E train only).
Copley Station on Boylston Street at Dartmouth Street.
Hynes/ICA Station on Newbury Street at Mass Ave.
Or you can drive, there is parking.
I usually take the train, since it is located in the center of Boston, so for lot of reasons it saves a lot of travel. Train runs often enough, and late enough till 1am. The only time I drove there was that when we went to the top of the hub, which is located one of the high floor in this building, since we had a baby and my father could not walk well.
This shopping center has a lot of stores like a lot of nice malls, but one of my favorites is Saks Fifth Avenue. I no longer need to go to NY for this. There are more restaurants inside, too. One time we invite people to Legal Seafood. They stayed in the Westin hotel. It is just great that we could go to the restaurant by walk inside, when it is freezing out. It is fun to look for non-famous, off the main street restaurants, but when you do not know the area that well and still want to do some Bostonian thing, Legal Seafood is the way to go.