I gave it a 3... I don't have the Platinum yet but I played 40 hours and all I have to do before getting the Platinum is to grind and finish the game with Jude.
You can miss items, treasure chests, random treasures, enemies, sub events, etc. and still get the associated trophies.
Tales of Vesperia (8/10) and Tales of Graces f (6/10) were way harder to plat and required organization.
Everything was rushed in Tales of Xillia, even the trophies.