[Spoiler:] By far the best boss design I've seen in a Souls game (light early/midgame spoilers)

I just started tackling the Abyss Watchers fight, and I think I'm in love. I came to the slow realization that the whole area between the bonfire and the boss room is an extremely elegant way to explain the mechanics of the fight (at least phase 1, I haven't yet beaten phase 2).

Allow me to gush for a moment. My mindset went from "oh shit, I have to kill 2 darkwraiths?! The solo darkwraith already kicked my ass" to "oh SHIT, I have to fight a million abyss watchers all at once? Better rush them down" to "wait a sec, those darkwraiths are distracting all the trash, so I don't have to fight any of them at all!" to "WAIT a SEC, the red-eyed Abyss watcher does THE SAME THING during the boss fight!!" The slow discovery of these things through observation of only what the game showed me in the lead-up caused my biggest "AHA" moment in Souls to date.

The Abyss Watchers are, so far, easily my favorite boss encounter of the game so far, and in my opinion, one of the most elegantly designed encounters in the entire series. The perfect blend of the joy of difficult boss mechanics (multiple opponents, multiple phases, and intimidation) and the joy of discovery. I can only hope the bosses continue to get better from here.