They are definitely goofy & over the top, with silly grins and bumpy knobby bone armor and hats, odd proportions, etc. 'Toyetic' is the word I would use, in that these look like miniatures that know and accept and embrace the fact that miniatures are just 'toys for big kids'. The remind me of He man toys or Army of Darkness or Skeleton Warriors (the cartoon show, not the warhammer unit). The Mortarch reminds me a bit of Mum-ra. The armor design calls to mind nothing so much as Skeletor's fancy gold armor from the end of the live action Masters of the Universe movie. I can see where more serious minded players would really dislike all of that, but personally? I grew up on that stuff, so for me the whole faction looks super nostalgic and just fun as heck.
So Yeah, I really like these. I like their concept & personality maybe a bit more than the models themselves. While I'm maybe a bit of an exception in really liking what GW seems to have been aiming for with these, even I can admit that they're maybe not as idealized a realization of that vision as, say, the Daughters of Khaine or Gloomspites or Nighthaunts were for their respective visions. Even for something self-consciously silly & toyetic, the proportions on the big bone harvesting monster feel off, and the crotch face is maybe a bit much. The noses in general aren't great, and the faces without them look better, imo.
But yeah, overall I really love what we've seen so far. The bishop looking four armed liche in the walking bone throne? That biz is my jam right there. Both the scythy ghosty caster and the bone caster modeled in the process of building a new ossiarch look absolutely fantastic to me. The Mortarch is amazing - though since Arkhan is a native part of this faction I'll probably build around him instead, at least to start. I like all versions of the stalkers we've seen. Probably my favorite version is dual wielding greatswords, but I do really like the heads on the halberd & shield variant. Catapult is great. I love the skeleton in the hamster wheel to winch the arm back - yeah the one bit of that model that I've seen a lot of folks complain about is my favorite part of the model.
I like the infantry and cavalry, but I worry that they'll just be too expensive for me to feasibly field them, especially since the infantry are on 25s or maybe 28s but according to people who saw them definitely not 32s. That implies that they'll actually be a horde unit after all, despite the fluff implying a more elite faction. I could easily see these turning releasing as a 5 man box for $40 with rules that make them only really worth running in multiple units of 30. If that's how they turn out... well, I don't know what I'll do. Maybe there will be a 'Legion of the Necropolis' variant list combining them with other death factions so I can combine the fancy new heroes & elite units with my existing undead battleline units.
It does look like Nagash, Arkhan, and the morghasts will show up as native parts of this army, which is cool. Fingers crossed for fancy new updated warscrolls that get retroactively applied to the existing Legions of Nagash entries. The morghasts especially have really been in need of an update for a while. Age of Sigmar has kind of moved on without them. At this point their stats & abilities fall sadly short of not only their points costs, but their concepts & models as well. We'll see, I guess.
Honestly, right now I'm just hoping that the negative reaction in some corners of the internet are overstated and that these models will actually sell pretty well once they're out, as I would really like GW to return to and expand on the ossiarchs in the future the way the stormcast line has seen multiple release waves. Maybe "Ossiarch Boneriders" for a faster variant incorporating bonemold chariots or an "Ossiarch Bonestorm" shooty variant with archer variants of the infantry and stalkers, plus some variant siege weapons to complement the catapult, like a massive ballista shooting the thigh bones of ancient extinct dragons, on a monstrous, for legged backwards centaur looking bone monster, with the upper torso in the back to draw back the bow?
I don't know, I'm just spit balling. Point is, I love these guys, I'd love to see more of them in the future, and I hope this pile eventually wins over enough players that GW thinks that's something worth pursuing.