I really liked 'Deep Breath' apart from three things:
The Vastra/Jenny "we're married." thing. Yeah, we got it the first time you told us, you don't need to repeat it ad nauseum.
"Oh gosh, isn't the Doctor old?" Why is that so very shocking?
Clara's reaction. As Vauxy said, she's interacted with every previous regeneration, seen the War Doctor, etc.
I'm glad that the episode was given as long as it was to get into its stride, it's a refreshing change of pace from the manic breathlessness of the last couple of seasons. The restaurant scene and the bluff against the clockwork man demonstrated that Clara has potential, I'm still not sold on her a season on yet.
Also, Eleven's posthumous phonecall seemed like a bit of a slap in the face to Capaldi, every other Doctor has been given his own chance to prove himself in the role and win over the fans, I feel like Moffat is treating the audience too preciously with Capaldi.
I'd say 7/10 - Good, but should have been braver and given the audience more credit.