Acts is Essentially about the lives of Peter and Paul. The two other notable characters within this book are Stephen and Philip - two deacons in the early church. It is a book about men - about their mistakes as well as their successes. It records their discouragements and their doubts as well as their victories. There is a principle here.
Acts is a book about learning to get back up.
The book of Acts does not picture Christians with halos. There are no stained-glass saints. Luke tells us about Christians the way they really are. We see the arguments that divided Christians. We see all of their failings.