Both sides look pretty nice in terms of visual effect, though I have found a lack of detail on the larger models lately (arachnarock and the sphinx). 40k-wise, the zombie dragon hits the spot for me as a Chaos Player. The wings will be perfect for Nurgle themed Princes or for Skarbarand.
The wraith and Banshee are alright - though it seems like they are going to be in those odd single figure plastic blisters like the storm of magic stuff. I really don't like how they have priced the SoM plastic singles as if they were pewter figures. It sets a precedent that I don't really like.
The Tzeentch herald looks great and is obviously a SoM addition. 40k players shouldn't need a whole lot of help coming up with ideas here, lol!
Well there you have it folks. At least one potential project there for me in the future. Now it is time to see what you 40k and Fantasy players think of this new gear!