I am very surprised that Yaxley can bring other Death Eaters into Grimmaud Place with apparition just because the secret was revealed to him. He won't be a secret keeper, after all. I wonder just how Rowling imagines this working. There seems to be an inordinate amount of strange stuff in this book about getting in to Grimmaud Place (and this raises the objection to apparating on the step of the building again as well).

Ron's re-introduction of the You-Know-Whoing of Voldemort is very useful plotwise. It keeps the taboo from being to immediately obvious, and stops them being swamped by bad guys all the time. And it makes sense in view of his character.

The Dumbledore subplot is tied to the hallows plot (which is also Voldemort's wand plot) through the young Grindewald, but it is not explicitly stated. And the subplot of the Sword of Gryffindor is taken up again from Dumbledore's will. I like how she weaves plot here. There is a very strong element of plot coupons in this book, but Rowling counteracts it by some strong plotting around it. I like how it also ties in with the uncertainty around Snape -- the trio assume Dumbledore managed to fool Snape, that it was Dumbledore who switched the swords.

And we learn about the exception to the first law of transfiguration -- no food from magic. And what I took to be an early indication of this (Hermione's attempts to fix the mouldy bread) turns out not to be: you can change food once you have it.

We also get the goblin issue by the river bank, which has been hovering in the background before, but comes to a head soon.