Nomads are nice concept. They provide lots of new possibilities, but they are very irritating me. AI loves bypassing my border fortresses using nomads, to raid my economy. What's more, I think they interfere with pathfinding a bit. I was constantly finding units I ordered to go somewhere stopped in halfway, and I guess it's caused by changing wormholes on nomads. What's more, nomads like to hover over normal planets(galaxy map), what makes it hard to enter that planet, and chaotic to even count enemy forces there.
And one funny 'bug' is that after some time wormhole guard posts do not always stay by wormholes.