Welcome, to a WORLD OF DUNGEONS

I recently had the pleasure of running Adam Koebel and Sage LaTorra's Dungeon World for the first time, and boy what an experience it was. Not only was this my first time running Dungeon World, or in fact any of the Powered by the Apocalypse games (named after the progenitor of the main rules framework, Vincent Baker's Apocalypse World), but it was also the first roleplaying experience of several of my players, who heard about tabletop RPGs through some of my gaming group regulars, and decided to try it out.
The first thing that struck me about Dungeon World was how easy the prep was. When I'm preparing for my biweekly Edge of the Empire game, my prepwork usually falls in the middle of the spectrum, detailing modular events and characters that I can drag and drop into the game as need be, without defining end states for any of those events. Usually, I just keep a few "glasses on the edge of the table": situations that can easily escalate given a bit of player interaction, but can otherwise be easily cleaned up and removed from the situation if they're not fitting. I rarely draw maps, only stat out key NPCs, and leave quite a bit up to my improv ability once table time begins.
Dungeon World seems fit to exactly my style of GMing. It seems like the game is specifically designed to encourage GMs to set up questions without answers, much as I do, and let players' actions inform the resolution of the session.
Here, lemme give some concrete details. For the first adventure, as I was crunched for time, I ran the I'm On A Boat adventure provided on the Dungeon World website. I looked at the document and at first was kind of confused. What would normally be a short bit of informational background text in one of my adventures was left as a question in this adventure. How did half-orc Tim become the first mate? Instead of writing answers, I went "screw it" and ran the adventure as is.
Amazingly, we went through the entire session without a single "booty" joke
What I got was something extremely interesting. Dungeon World has an extremely interesting mechanic wherein player actions are tied into specific dice rolls called Moves, and the results of Moves are very specifically laid out in the game text. One such Move, Discern Realities, is an equivalent to a normal game's Perception check, but instead of just allowing players to ask whatever they want, it constrains their results to a list of predefined questions they get to ask the GM, one of which being "What here is not what it appears to be?"
The fact that players have this question sitting in front of them at all times has a weird effect: it means players are constantly assuming that there's more to the situation than what they can see. That, therefore, leaves them trying to extrapolate the details on their own. My players saw the situation aboard the Salty Mare, the boat described in the adventure, and assuming there was more than meets the eye, began to out loud postulate on the secrets of the ship, one of which being that Captain Cassandra Cassius might have been getting to know one of the passengers in the biblical sense.
While they were just postulating blindly about the game, I had those questions from the adventure in the back of my mind, and as my group was trying to think of the answer to the "mystery" (which in fact had no answer, and only existed insofar as the Discern Realities movie implied its existence), I managed to leverage these player expectations to answer these questions on the spot, and develop the game world right then and there to fit to the most interesting of the ideas proposed to my players. To them, it seemed like they were uncovering some grand mystery I had planned out from the start. To me, I was just using what they were expecting to feed my improv.
Now, obviously this can work for basically any system, but Dungeon World is designed in such a way that players are constantly confronted with implications about the world, from the mysteries implied by "What here is not what it appears to be?", to the fill-in-the-blank Bonds their characters share with the party members, which imply a long and checkered history between party members, to specific class features like the Fighter's Heirloom, which in its existence implies a sort of family that would pass an Heirloom down. Dungeon World down to its very mechanical level gives the players questions, and as they answer them, they give the GM a constant drip-feed of ideas, the most interesting of which the GM can take, or subvert, making the players feel like they're exploring this well-defined world when, in reality, they're helping define it.
In fact, Dungeon World does a neat trick where every character class, both at creation and in its Moves, requires players to explore and think about the world. From Bards having to describe the works of art they're pulling from when they use Bardic Knowledge. Rangers are built to get a constant influx of knowledge about the monsters and animals they encounter. Clerics get to describe not only the god they worship, but the trappings of exactly how their religion operates. No matter what class you pick, you will always end up learning about the world, and defining things about it.
I think the I'm On A Boat adventure also helped me figure out how to GM Dungeon World. Instead of actually defining the adventure and world beforehand, the adventure encouraged me to leave setting questions, presented only to me, open-ended. Whenever the players in their blind fumbling gave me an interesting answer to one of those questions, I could just slot it in as the answer, and pretend it was that way all along.
Now, Dungeon World isn't necessarily going to become my go-to for all things fantasy. Character creation is extremely focused, forcing characters into very trope-y roles based on their character classes, so if I was looking for something a bit more character focused, or a bit further from fantasy as it's been canonized in pop culture, I might turn to some of my older mainstays, like Pathfinder. However, I think Dungeon World's ability to tell stories about worlds, and to develop intricate and interesting settings and moments, is perhaps unmatched, and I'll probably be coming back to play more as soon as I can.