I ought to hate it. I do, happily, hate aspects of it. The names are horrendous - not just the druadin=dwarves, orruks=orcs nonsense, but the terrible unimaginative pseudo-exotic rubbish monolingual English speakers come up with when they try to think of a place name that sounds fantastical ("Ghur", "Ghyran", "Ulgu" - give me "Bretonnia" any day). The "Stormcast Eternals" concept is dreadful (you can just imagine the conversation in the board room: "People love Space Marines. We've got to find some way to get Space Marines into Warhammer"). It seems on its face to be have been designed deliberately to reward system mastery, which is an approach I instinctively despise. I don't understand what's going on with Slaanesh and the apparent replacement with the Horned God; doesn't the Horned God overlap too much with Nurgle, and isn't Slaanesh kind of cool? And, once again we get huge faction proliferation, mostly at the expense of humans (I had to search really hard to find any information on the wikipedia entry about humans).
Plenty to dislike, then. But, damn it, I do find plenty to like, too. I think the distinctly Moorcockian shift is welcome, even if the Order/Chaos/Death/Destruction split into super-factions doesn't make any real sense: at least it's a bit different from your typical bog-standard fantasy setting. And the separation of the setting into different realms or spheres is reminiscent both of Planescape, which I like, and also Gene Wolfe's The Wizard Knight, which I also like, and that is not to mention Moorcock's multiverse concept itself; all good so far. There is enough actual weirdness in there to genuinely intrigue me: Slaan floating around in cosmic vessels remembering
I think you also have to hand it to Games Workshop for, well, "going big or going home". They went big with Age of Sigmar. It's what there was before, not turned up to 11, but 111. It is absurdly OTT: Bonesplitterz? Aleguzzler gargant? Maggotkin of Nurgle? Swifthawk agents? The lion raiders? Are you kidding me? It's only a few steps removed from what a 9-year-old boy would come up with over the course of a weekend. But they went for it. You sort of have to doff your cap to them. In a strange way, my reaction to it is a bit like my reaction to James Cameron's Avatar. It's not actually very good. And yet.... it certainly was a whole lot of movie. In the same way, Age of Sigmar is a whole lot of Games Workshop. And ultimately there is nothing wrong with that.