There are a couple of things that stand out about Boston.
First, the University atmosphere. Guess this is because the city has so many schools. It feels as if the whole city is a large campus. And so it is beautifully welcoming even to the value conscious traveler. There are cycle paths everywhere. Food is great and affordable. Almost all around have an intellectual streak.
Second, the History. Being one of the oldest cities in the US, it has a wealth of history and culture. Very unlike a lot of other US towns I have visited in the past. So for a culture buff, there is a wealth of things to see and do.
Third, it is very walkable city. Now this is one of the things I used to find disconcerting about the US, coming from Asia. Most other US towns I have been to are so vast and widespread that driving around becomes a necessity. In Boston, one day I started from the MIT campus in Cambridge on a morning walk, and began walking around aimlessly looking at interesting landmarks. Before I knew it I was in downtown Boston, amidst the historic landmarks, tall skyscrapers, and pretty markets and piers.
For a traveler from India, I would consider it akin to a Pune, that isin't too far from the bustling metropolis of Mumbai (that is more akin to NY).