From what I've read/heard on other forums, the core rules are very similar to LotR SBG (in the same way that Legends of the High Seas and Legends of the Old West use the same engine), and it strongly encourages campaign-play in which you manage a group of gladiators who can become better warriors, learn new skills, and gain favor with the audience and Emperor as they progress through their matches.
Sounds really cool, and the amount of info is supposed to be well worth the price, so I think I'll be picking this game up.