Already ordered the book and will definitely get some demigryph knights at some point. But I see a lot of guys already decided on two boxes worth of demigryphs and I'm surprised. They're not going to be worth the points to run them with a rank because the real benefit comes from the mount, whose attacks you wont get from the back rank. You might want to run them four wide, but 5 or 6 wide is a bit ridiculous and who wants to have 2 spare models lying around at $18 each?
Then you've got the revamped steam tank with super duper impact hits and random movement for 50 points less. That thing just got a whole lot more awesome. And with the mortar nerf it looks like volley guns and hellblasters are going to be the new artillery choices, so you've already got a full rare section before throwing in another 350 point unit (+/-) of 6 demigryphs, or even a pair of 3 demigryph units. They do look good... on paper, but certainly not mournfang good. I'll be surprised to see more than 1 unit of 3 or 4 on the table very often.
As for the big models... I hope they're good, but I've got my doubts. The War Altar sounds like it will still be pretty good and worth while, despite having gotten some nerfing. The new one is definitely better than the one I've got, but $50 better? Nah. As to the others... well, I already mentioned that incredibly full rare section which is going to be problematic for the big carts. Then instead of artillery, I've already got cannons. And the buffs? They seem too one-dimensional and too short ranged to be very good. After impact hits, I can't see either of these being any good in combat, so at least some portion of their points cost rationale will account for the combat possibility, but my guess is that these guys are just going to free CR whenever they do get into combat. I find it hard to imagine how they will be rationally priced. I'll be happy to be mistaken, but I think the big carts are going to turn out to be a big disappointment.