I missed Hogwarts and the structure, but at the same time I thought the biggest problem with HBP was the fact that Harry was still at Hogwarts. The book felt a bit stagnant to me because Harry needed to be elsewhere and JKR was just using excuses to keep him there.

I agree though the DH had an unecessarily messy plot. I wish it has been simpler and that Harry had been given more time to dwell on the consequences of the action sequences.