Dungeon World is not great as a PbtA game, but it still works.
I keep meaning to check out Chasing Adventure, which is an attempt to make a more PbtA Dungeon World, but haven't gotten around to it.
I think a big part of what made Dungeon World a huge success and very popular for a long time, and ironically enough, thus contributed significantly to the success and spread of PtbA games is precisely that.
Dungeon World isn't really, design-wise, a pure PtbA game, it's almost like a hybrid that's mostly PtbA but also includes significant OSR/earlier D&D/AD&D heritage, and when you run it or play it, you can actually lean it significantly one way or the other.
Personally I'd say if you're a fan of PtbA games already, and want to try a fantasy one, there are better options. But if you're not already a fan of PtbA games, it might well please you a lot more than many pure PtbA games, or simply be a lot more accessible. It's also weirdly highly compatible with most D&D/AD&D (1E/2E) material, arguably even later stuff, where other PtbA fantasy games tend not to be.
I'm told World of Dungeons evolves Dungeon World into a more successful form. I have not played either.
I would say whoever told you that is flatly wrong. World of Dungeons simply a vastly watered-down/simplified version of Dungeon World. If you're an experienced PtbA game-builder, and you want to build from there, yeah it's a better chassis to start building your own classes and so on from. But the actual game? It certainly isn't "more successful", it's just hugely pared-down, which is kind of missing the entire point imho. It's also no better as a PtbA game than DW.
It's a pity because I'd love to see a game which was an evolution of Dungeon World, rather than a simplification or a completely different, more classically PtbA-ish direction, but the closest we've got is stuff like Class Warfare, which isn't quite it imho.
If you could provide me a link to the Dungeon World Guide, I would be most appreciative.
It should be on the page below on the official site: