i liked the companion quests. except lilly, triggering her second part was kind of a pain. and her voice annoys the hell out of me. at first my complaint was that the triggers all seemed random, but after a few playthroughs and a visit to fallout wiki, i'm kicking myself for not really thinking about it; the triggers really make sense and i appreciate the way obsidian tried to create a real life flow to it. i also found all their stories solid to compelling, especially boone's anguish and cass's despair. and c'mon, how do you not want to help rex? of all the companions, i get the most satisfaction from helping him. especially after the king and julie farkas speak so lovingly about him. actually, he's the only one in the wasteland that's loved by everyone, ncr and legion included. funny rex note: while walking through ncr camps, many ncr npc's will walk up to rex and talk to him lol ignoring the two humans. there's funny stuff in this game, but that cracks me up every time.
actually i have one valid complaint: many triggers are one time deals, i think that was a mistake.