Yea...I only had someone come to the island via Streetpass.
Regrettably, Tomodachi Life is regrettable. I think it let most people down from what I've seen here. I'm still going to pick it up at some point and see for myself.
I think if they had added more multiplayer features to it (like in ANCL) it would have been way bigger than it ended up being.
It does get dull, mostly because the Miis ask the same things of you.
Though, the entertainment value depends on what you do with it, I suppose...in my case, I just made a bunch of Miis based off of anime characters (with names and everything) for amusement (and because I like writing crossovers, and thought it'd be hilarious).
I also made a rule where everyone starts as a kid, and they only get to grow up if they get married (though, I currently do have the children feature turned off).
I think the funniest moment was the love triangle between Quatre (Gundam Wing), Hikaru (Magic Knight Rayearth), and Ken (Digimon 02)...Ken won. XD
Watching these anime characters rap in the boombox challenge is also usually hilarious, because for many of them, it's very OOC.