Maius Intra Qua Extra

Last sentences first.... it may not have had galactic/universes wide importance, but the crux of the matter was the complicated personal relationship between the Doctor and Donna, and where Donna truly belonged. I think that I agree with you, that is where it truly shines!

It's true, the listeners, while we know it wasn't done intentionally, truly feel like Donna's been deliberately put into a trap. Rudolph's actions once he finds out what is waiting for them, really reek! Not to mention his "mommy's boy" behavior. He was just cringeworthy at times, and absolutely not worthy of Donna Noble, and neither was his mother.

The emotional moments between the Doctor and Donna, where he truly does begin pouring out his hearts to her, had me crying for him. You can tell he truly admires her, doesn't want to let her go, but will if it's truly for her happiness. He would shatter without her (and did when she did have to leave).

Donna truly acts more regal than any of the so-called royals, not resigning herself immediately to the situation, but looking to act, to find out what is really happening. When she does find out, she, the Doctor and Hortense work out a plan, but she is willing to risk her own death to save "her people."

When the Doctor offered to die in her place, and Death responded by saying he was unloved, I wanted to practically scream out that he was loved; each of his companions, in their own way, loved him, even as they may have suffered. I'm sure Donna does, too.

As you say, they truly did save the best for last. It was truly an emotional rollercoaster, and Donna discovered that her true place was in the TARDIS, at the Doctor's side, for as long as she possibly could be there. And it was done simultaneously with their witty banter!