I actually quite liked this series... to a point.
The main problem I had with this series was the patchy writing. A good few of the episodes were written for a generic Doctor á la 8 through to 11 - someone sprightly, energetic or physically at his peak. 12 is none of those things - he's a brooding, grizzled "survivor" Doctor with a grumpy demeanour, but a heart in the middle of all of it (which we didn't get to see much of). The episodes actually written with Capaldi's Doctor in mind were much better, whereas other ones, such as Into the Dalek and Time Heist, would have suited Smith or Tennant. Listen, by contract, was a perfect episode for Capaldi.
I didn't like Dark Water - imagine a child whose parent has just died and been cremated watching that! - but Death in Heaven picked it up a little for me, and the absence-of-Gallifrey rage was the moment that I thought, "ah, there you are, Doctor." All in all, an OK ending to a series, although...
I want to get Clara back, somehow; even though both she and the Doctor have lied to each other, they're doing so (for the first time, I notice) in order not to hurt each other's feelings, or betray their own personal disappointment. Clara came into her own this series - although stifled by Danny Pink, who I found really annoying by the end - I'd like to see her as an independent companion again. I know she'll be back by Christmas, so it'll be interesting to see in what capacity.
All in all, a bit of a muddled series, held up (just) by good performances in terms of the acting, but marred by a mixed bag of writing. My favourite episodes, in fact, were Robot of Sherwood and In The Forest of the Night - the more light-hearted ones - as, frankly, they were more fun. It is, after all, a children's show, and a darker Doctor doesn't have to mean the absence of jokes at all!