I've built several of the Architecture sets and by far, this is my favourite set.
First of all, there is no play value as it's meant to be built, displayed and swooned over. As a display model, it's gorgeous with the subtle curves and sculpting of the two taller towers. I also love the variety in the choices in style of architecture. Unlike the London set which had a mishmash of different scales, these representations have similar scales, as much as is possible at microscale, resulting in a much more pleasing display.
From the perspective of construction, it's not overly hard for experienced builders, but there is a great variety of SNOT techniques and I learned a lot of new ways of building. The final tower is so satisfying to complete, with such an elegant an ingenious solution.
Finally, there is a real plethora of new parts and parts in new colours. It's a great set, even simply as a parts pack.
Hats off to the Lego designers, you've hit a real home run!!