Because of the nature of the episode, being both spoiler-filled and a two parter, and the removal of the Missy revelation scenes, it's almost impossible to give a worthy review, therefore this review won't be that great compared to normal.
Dark Water sees the return of two-parters to the series, something much sought after since they were put on the back burner. This episode leaves all the epic drama seen in the trailers for the finale episode, and focuses on pulling all the strings together for the viewers to understand it. While this didn't work well for Time of the Doctor, this is pulled off very well in this episode, mainly relying on the series arc to keep people interested. The episode will still leave people with many questions, only answering a very small few. The episode feels very much like exactly half of the story, and I often think this story will work far better as either a double episode or watched one after another, since after the cliffhanger, I couldn't help but feel somewhat disappointed about the lack of information revealed. That's the point though, right? The episode was very fluid and it feels as if it had just shot past without feeling rushed.
Central to the plot is the relationship between Clara and Danny. After Danny found out last week about Clara staying on the TARDIS, we see the episode open as she begins to answer his request to be truthful, after spending a long time working out exactly what to say and the events of this phone call kickstarts the entire finale. Danny Pink has to face his dreadful past and, while it was almost exactly what was expected, it still was a major factor in making the episode heart-wrenching.
This episode is exceedingly dark with the events surrounding those who have died. This episode may sit uneasy with those who have recently lost a loved one, perhaps offend some religions and could even traumatise children, especially those who are not yet old enough to realise the show is fictional. I believe only the latter will really come to bear though. Either way, there will be plenty of nightmares going around!
Despite the extremely dark nature of the episode, there's actually a surprising amount of comedy in the episode, mainly coming from Missy and Seb. Moffat is clearly keen to reference plenty of things, from at least three separate Apple references (even avoiding using a trademark, which was bone-chilling) to a Malcolm Tucker joke.
The BBC have made no attempt to keep the Cybermen's return to the show a secret, from releasing a promotional image before series 8 started airing to showing them in the trailer to releasing a preview clip from the final 5 minutes of the episode. Fortunately, the episode is written with the knowledge of this in mind and lots of subtle, and not so subtle, hints are dropped in throughout. This is pulled off surprisingly well and how they are woven into the story is done with gruesome ingenuity.
As usual, all the actors are simply beautiful in their portrayal of the characters. Capaldi and Coleman are incredible in their roles opposite each other as they both try to focus on the traumatic times ahead, while Samuel Anderson definitely does his finest performance on the show. Michelle Gomez, as Missy, fits her role as disturbing very well. On the note of disturbing, Chris Addison is simply hilarious as the person who welcomes the newest deceased.
The directing is, on the whole, very well done although there were some glaring and basic continuity errors which sadly spoiled it a bit for me.
The episode works extremely well, teasing us along. It's thrilling, bone-chilling, funny and exciting. I would definitely recommend a watch, and would probably rate it highly, but I will wait for the finale before rating.