That was bad. Just really poorly executed.
I'm glad that Moffat came up with the wonderful idea to have a hybrid Dalek race and have Clara turning into a Dalek. Really groundbreaking stuff there.
All the Doctor/Davros scenes just dragged on and on forever, and then turned into constant "Aha, you fell for my trap" "Ohoho, but that was actually my trap" nonsense.
Beyond that, why with this insistence that there has to be some terrible secret behind the Doctor leaving Gallifrey? I wish Moffat would just fuck off with this nonsense. The Doctor's life doesn't need to be a constant run of secrets and prophecies and horrific revelations. The Doctor fled from Gallifrey and rebelled against their customs because he was bored by the existence there and hated the stuffy bureaucracy and their bullshit "non-interference" policy when terrible shit was happening in the universe. There's an elegant simplicity to it, but that's enough for Moffat.
Why can't we just leave the past alone? Here's the Doctor. He goes on adventures. Stop with the turning the Doctor into some mythological, godlike figure who always has to have some dark secret waiting at every turn.