It only tells backstories of backstories (If that makes sense) And random rid bits of info like history of exotic weapons and in the new DLC if you read the new ghosts you'll have a different perspective on the awoken and their queen. For example in one of the last ghosts you get you read a conversation Varikis, The Loyal has to himself about if it was right to not join the Fallen during the rebellion + latter ghost states that only Varikis and The Queen had the keys to Skolas cell indicating that Varikis might have let Skolas out in the first place to rebel the queen or to prove his loyalty for the house of judgement. It's some good stuff I recommend reading it.