Boston very walkable, in my opinion. While the streets arent generally straight, the city's not BIG either - and its pretty safe, so theres not generally big industrial dead zones, so it's not that hard to walk from one side of the city to the other. In fact, I have. Dorchester to Cambridge. The only real problem is knowing the streets well enough to know where you're going and once you know that the problems moot.

I've backpacked across Europe and Roadtripped across the US as well, so I've been to LOTS of cities.

Compared to US cities, Boston is supremely walkable (cow path roads aside). The city center was designed people first. So much of the city was laid out before cars or MBTA came about. Even other big US cities struggle to say that. San Francisco, while... 'walkable' has a steep hill problem that makes things problematic for people with disabilities or arent super fit, requiring people to drive to use public transportation. I'm disabled and I've issued with their transportation not stopping at all because theyre full and im left stranded. Its not great.

European cities are walkable only because they were designed and build when walking was the only means of transportation. I've lived in Leeds. Downtown Leeds is just a giant walkable shopping district, residential neighborhoods is GARBAGE.