Not my favorite model, though I like her more than I though I would from the silhouette. The veiled skull is cool, though her head seems a tough too large for her body. She's a bit statically posed, and doesn't do enough with that huge base, and looks to suffer from some fragile/wobbly thinbit connections, but most of that can be fixed up with some scenic basing. I like the rose thorn motif, which should tie her reasonably well into the existing death line and in particular the graveyard scenery kit.
Though I was excited by the rumors that Isabella might be returning as an important character in her own right, I'm glad that the mortarch of Grief actually turned out to be an entirely new character. Death in AoS desperately needs new characters, imo, and if Isabella does ever return I'd prefer a characterization that actually moves her forward rather than making 'sad for vlad' her defining character trait.
Other than that, there's not too much to say about Olynder yet, at least not until we see her rules & full backstory, but for now I'm reasonably interested. All in all, she seems pretty cool, imo.