An old man, doing the same thing, over and over again,
for 2 billion years, whilst talking to himself. If the BBC intended this as an allegory for senility, it was spot on. Sadly, I fear it was intended as an exciting TV show for kids, and so it was really fucking boring.
It can't have helped that I have no idea what this "hybrid" business is about, nor why a "confession disk" is a tiny prison, nor why The Doctor was stuck inside it. Come to think of it, how did the disk make its way to Galifrey, given that Gallifrey was locked away where no one could reach it? And why didn't The Doctor regenerate when he burned his body to power the machine? So many unanswered questions - there should be a Red Button feature to future broadcasts that could explain these things as they become relevant.
Very much a Curate's Egg, these modern Doctor Who series (which probably isn't all that different from how it used to be, if I'm honest).