Never used it before
I got the game from humble monthly. I bought the season pass after a few hours in because I enjoyed it and wanted to see more what it has to offer. I did my first raid lair as a Seeker with 6 people from a clan called Cosmic Jelly. They were guiding one of their clan mates too. Raidleader was very helpful and patient. The rest of the people were very helpful too. One of them was disconnected around where we got fire out of a cannon and could not rejoin so we have to leave the guided game. They invited me back and we continued. We wiped 2-3 times at the last boss but we cleared it. I'm very happy that there's this system in this game. I've done 3 nightfall as a Guide with my mate who picked up the game same time as I did. I'm 356 and he's 353. I don't expect every guided raid I join in future to be as smooth as my first one.
Tried in early stages and had to teach a clan how the raid mechanics work. 2nd try only 2 people had mics. 3rd time was with my clan. A player left to change characters to help an area run smooth. Received 45 min penalty.
For nightfall, yes. Raid, won't even waste my time.