This is our second time staying at Tim's place, and I'm convinced it's the best place to stay for exploring Boston.
Easy, off-street parking is available, which means you can use your car when you need it. However, 90% of the time we didn't need a car and either took the T or walked everywhere. We walked to Red Sox games at Fenway, walked to Boston Common for Freedom Trail tours, and even walked a couple of miles to Boston Harbor for Labor Day fireworks.
You're on a quiet street, but just a couple of blocks from all the shopping, dining, etc. that you could want. Tim was responsive and fantastic all along when we had questions, and hopefully, we'll stay again a third time whenever we come to Boston again.
If you're looking for a walkable, convenient, and safe location to explore Boston - this is the place.