I've been following the thread without an account for ages, but now that I've actually seen some links I figured I'd join in the discussion.
Knight Bus: I think it looks great, no complaints at this point
Expecto Patronum: Great, might get two for more dementors
Hagrid's Hut: Looks great to me, although it does look like just a facade and I wish it was a full building. I might modify that.
Triwizard Challenge: I like that the broom can actually be stood on, might modify my other brooms to make them work the same way. The horntail is ok...just ok.
Clocktower: I think this looks great, although I might make the clock portion one story taller, it seems a bit short, but understandable for price/piece count. I actually don't mind Hermione's legs being a 1x2 brick. Maybe a dress piece would be better, but I'm not really disappointed with this.
Overall, I'll be buying them all, of course. I haven't made modifications to the first wave yet, but may now that I have more castle to look at and scale it around.