Luke, if you're reading I hope your team takes what I am about to say to heart.
I'll preface by saying that this isn't an official review, I haven't beaten the last boss, and anyone is welcome to disagree with me.
So what I want to say is I do not think the boss fights in this Raid are good. Mechanically, they are very interesting and uniquely complex and I enjoy that about them. The challenges in between bosses are also nice (especially the second one) and the scale of it is fantastic. It's a giant Raid and it'll be lots of fun when we're blowing through it.
But I don't think it's anywhere near the Vault of Glass. King's Fall to me is what Crota's End was supposed to be, only even then Crota's End managed to keep some of what the Vault of Glass had:
Player Choice
List any encounter from the Vault of Glass and you will see that there are at least 3 different ways to do it. There are different tactics that can be employed and players can change up how they tackle things. Gatekeepers in particular can be tailored to the group as needed: Two people can go in one portal and then go in the next; both portals can be done simultaneously; or one person can solo both portals and pass the relic off to people on the inside.
I love that kind of thing. Every Raid can potentially be different because it will play to the strengths and preferences of the group.
This was diminished in Crota's End, and I don't see it anywhere in King's Fall. These objectives are too specific with little margin for error and I do not see much room for creativity. It's entirely possible that I am judging this prematurely and I'll be pleased to eat crow when alternative strategies are discovered. (The Crota fight bored me when everyone went to the bottom room to DPS Crota and the Ogres, but it was fun again when we started using the left side and the window was better... until it became the only way to do Hard mode.)
As it stands now with King's Fall, I feel like everyone is doing the exact same strategy and I don't see us doing anything else other than perfecting that strategy. In this Raid, there is the right way and the wrong way, and that is not what I think a Raid should be. Vault of Glass certainly wasn't when it launched and it still isn't today.
I'm not asking for platforms where you can ignore the mechanics, and I'm not asking for the fights to be watered down. Hell, I don't think King's Fall is difficult enough. What I am asking for is flexibility where it's up to the creativity and the strengths of the players to solve the puzzles and pull through. Vault of Glass always let the player tackle the encounters how they wanted. King's Fall is basically "DPS or get the fuck out".