While questing behind enemy lines I came across a city with a river, where some rebels were fighting the Imperials. Anyway, while I was doing some quests there I saw someone from a rival faction run up to the quest giver. I followed him around to the NPCs he had to talk to, then to the imperial guards he had to fight. After the guards had broken his initial attack and started to hurt him a little bit, I emerged and let my blades tear him apart, only to disappear into the shadows seconds later.
Yes, this is a cheap way to get kills. But, not really that cheap. I knew the dangers of questing in Cyrodiil, that's why I saw him and he didn't see me. I really like the vulnerability that Cyrodiil introduces. The harshness, the brutality of war. Running around Cyrodiil reminds me of games like DayZ or Planetside2, the world doesn't revolve around you, or your faction, it's a living breathing world that cares not weather you live or die, weather you get a fair fight or get ambushed doing quests. The lumber mills keep cutting, the farms keep farming.
I don't think I would have purchased this game without Cyrodiil being like it is.