What makes these stories work in my opinion is that the author understands how different the Roman world is from our modern world. This shows in attitudes to violence, religion, honour, class, poverty, law. These are not modern stories and characters put on a Roman set. They are Romans (& their Romanising and resisting subjects) living in a Roman world. That can make the book a bit harder to read, but it also makes it more interesting and fun to have read.