Now that the movie is out, KNB did... an okay job, I think. Could've been better, could've been worse. Kinda like the whole movie.
Sure, Falconer looked a bit on the short side. Like, shorter than any of the background Predators from AVP.
And when the masks/armor were off, like on Classic or Beserker at th eend, there was no real moisture/slime to them, which gave them a serious resemblance to the Preds from AVP. (Which, unlike many people, I never hated - I just figured hey, there are Preds with different facial features just like there are people or dogs, and this one's just a bit uglier.
But the overall designs were pretty solid, and they functioned well. I liked the idea of the bones and skulls grafted onto the helmets, too.
I'd put these Preds below the ones from the first two films (of course) and below the work on AVP:R, but probably above the Pred work on AVP or around the same level.
But honestly, I expected so much less from KNB - I haven't been impressed by their practical effects in the past much at all - that this was really more satisfying than I thought.