If I was brave enough I'd do a video review but I'm not so you have to just read instead! This was a present to my son from his Dad and was welcomed with open arms by my Lego mad boy. My son is autistic but has fabulous imagination skills when it comes to Lego and lots of things have been created from various kits over the years. So....
Firstly the price: This is a very expensive kit for a child who wants to build it and then break it into thousands of pieces to build spaceships from the bits (normally what my son does). However, if a child likes building and keeping their creation from a kit then this is fabulous - the final finished article has a moving staircase, revolving bookcases, books, lots of fgures but no Ron(why Lego - just why have you NOT included Ron?) It DOES however, have Dementors which my son thinks are amazing monsters.
Secondly - ease of construction: Having spent many a stressful hour building Lego Star Wars spaceships which my son then destroys to build something else I was wary of this. My heart sank when we opened the box and no fewer than 10 bags of Lego fell out plus three thick construction booklets. BUT - it was actually easy - really good and clear instructions with one bag making one thing and the next bag another mostly. This was good as it meant we could build the castle over a few days but that Bag 1 could be opened with all the figures and the beginnings of the castle - this meant my son could play with it right away which is just what you need with a kit this size. My son being both autistic and Lego mad at age 8 built this casdtle practically single handed as the instructions were so good. Granted he had constant supervision and a bit of guidance but mostly he built it himself from the very clear instructions.
Thirdly - final product: Looks absolutely amazing - it needs a board because it will break if you try and lift it without but as long as you have this it looks fantastic and should stay looking so. My son has actually left this complete and is still playing with it.
Detail is amazing with little Lego food in the Dining Hall, a bookcase with sliding doors in Dumbledore's office, potion bottles and stoppers, a copy of The Quibbler complete with Harry Potter headline in the common room and even a chandaleir.
Final opinion - expensive kit yes but well well worth the money for the hours of entertainment and play it offers. Well done Lego.