I thought Crest of the Stars was great, and felt that Banner of the Stars I could have been a lot better...but... seriously Banner of the Stars II couldn't have been any better. Everything seemed perfect, all the little details I disliked about BotSI were gone, and they brought back that Sci-fi/adventure atmosphere which made me enjoy Crest of the Stars so much.
If BotSI was close to a snorefest to me, BotSII was the total opposite. Full of non-stop action, I was literally sweating for the characters. Very very good series overall, highly recommended.
That Passage of the Stars extra episode (available on Bandai's Anime Legend boxset) was also very interesting, it was fun to see Lafiel's parents having an episode of their own.