Link Button Placement
One thing in the UI that sticks out to me is the placement of the button that navigates to the link screen from the portal screen and the position of the link confirmation button on the link screen. Specifically that you're likely to accidentally link to the portal of the first key that loads if you tend to hit the link screen button in the middle or top—all it takes at that point is the phone rocking a bit in your hand or you finger jittering a little.
In 1.x/[Redacted] I never had the problem with accidentally linking due to button placement, only due to having the "tray" open and a key suddenly loading—easily prevented by closing the tray when you have the right portal selected. So really I was thinking that all that needs to be done is moving the button that navigates to the linking screen down a little bit so that it doesn't have an active area that overlaps the link confirmation button.