People usually talk about the bad, and not the good. If something was working just fine, we wouldn't discuss it, correct?
I suppose there's always the risk that you'll run into someone nasty - personally, I haven't done that before. I've also had a few nice conversations with people from all over the world, which is cool.
The main bonus is the island-exclusive items that you will be able to get with Club Tortimer. And you get to play with people from all over the world and have emoticon conversations!
Anyways, I heard from someone else that any items you put in the box stay in your possession, even if the Wi-Fi switch gets flipped. I've never had to test that theory before, but that's something to remember if you do come across some beetles or sharks.