I really have loved every Boston I've ever met (dog parks, pet stores, etc). They just seem sooo friendly. Definitely strong for little guys, and muscular, and agile. I love it! I have looked into the breed a bit and there's a few forums like YT for them (One is called Woof! I think?) and I'm sure you could find out some more info there.
I research different breeds sometimes because I think it's gonna be a little bit before adding a 2nd dog so I really wanna be sure.
BTW, Zipper is adorable.