besides Mrs Smith? Sir John never said anything about Willoughby's other relatives (and he didn't actually say anything about Mrs Smith, as far as I can remember).

I also don't remember Sir John saying anything specific about Willougby's character other than "As good a kind of fellow as ever lived, I assure you." And is there anyone of whom doesn't Sir John speak well at this point?

The other pieces of information that Sir John gives about Willoughby have little to do with Willoughby's character (except in the imagination of Marianne!):

"A very decent shot, and there is not a bolder rider in England"

"he is a pleasant, good humoured fellow, and has got the nicest little black bitch of a pointer I ever saw"

"he has a pretty little estate of his own in Somersetshire besides"

"I remember last Christmas, at a little hop at the Park, he danced from eight o'clock till four, without once sitting down. ... and he was up again at eight to ride to covert."