First, this is the best book since PoA. I was disappointed with OotP, but this one seems to be back in line with the others. It was a perfect set-up to book seven, which I officially can't wait for...
...because I want the kids to figure out that R.A.B. stands for Regalus A. Black. DOY. Come on, kids, get with the program. A dead mentor doesn't give anyone an excuse to overlook something so damn obvious. Gah.