[Armin considers a moment, then makes the connection private and puts up mental barriers - even if he tells Rise about his abilities, he's seen the way Matthew responded to one of his more innocuous skills. He doesn't want to see that kind of fear and distrust on a larger scale.]

There... a lot. First of all, you can make a connection private like this - so only certain people can hear it. You can look back through the network to revisit conversations, or see things you missed. You can stream your senses to other people, or listen in on theirs if they let you. You can project your voice and your image over the network, or share your memories, or even create virtual realities.

...You can also cut off one or more of your senses, locate a nearby Traveler, turn someone into an infiltrator, hack into private conversations, or even potentially read someone's surface thoughts. Although it's possible to learn to protect against those things as well.