I don't like Street Pass, I think it's a stupid way of giving out promotional stuff. But then, this is the frustration talking - it took me forever to rebuild Norende in Bravely Default, and it's nothing short of a miracle that I managed to pick up an Eon Ticket considering how scarcely Nintendo handed it out initially. Plus I have several puzzles I really want to finish, but I doubt I ever will, as the only way to get some of the pieces is via Street Pass...and then only if the person I happen to pass has the piece I'm looking for.
It works well in theory, but the biggest problem is that its only really people in Japan that can utilize it properly, as practically everyone there has a 3DS. I usually encounter two or three people when I take my 3DS out, but that's primarily because I almost always pop into my local GAME store every time I go into town, and the staff have theirs on hand with them at all times. Otherwise, I hardly ever get a hit. It's not a very Western-friendly feature, really.
Still, it could be worse...at least it isn't vital to finishing any of the games I've played. Not yet, anyway. It's just extremely frustrating that they offer useful or desirable things exclusively via Street Pass in this country when practically nobody uses it.