The cloaking effect is not seen by other players. I've seen several other people reporting this problem, so as of now it only works on NPCs which is...disappointing to say the least. This is easily the coolest cloak addon and it doesn't even function like it should.

(Edit)
Seems to sorta work when I was testing in peer-to-peer. But whenever someone uses cloak, EVERYONE is cloaked at the same time. It's very clearly not working as intended which is a shame! I just hope these can be fixed, otherwise avoid using this in multiplayer for now.