Pretty much what sora said and to add in - you only get fairies and plat armours as rewards, and there's a cap on how many you can get. You have to weight whether it is worth it to you or if you rather farm normal stuff instead. Subjugations are in no way necessary other than getting some fodder that you can easily grind up on dailies.
Also, it runs for 4 weeks if they do the same as DMM, with other events coming later to run alongside it. It's something to throw charisma at when you have excess.