Warning: Full reviews contain spoilers for those who have not yet seen the episode. Updates will be made as more reviews come in.
(* = newly added)
*
Clique Clack: "No, what has me convinced, more than ever, that the writers are listening to me, is where they’re going with Gwen this season. Because it is amazing. It is everything I didn’t even think to hope for because I thought they were about as likely as Morgana having plot coherency."
*
Critictoo: "This second part first then decided to exploit the sacrifice to come, that required to close the doors of the spiritual world and stop The Dorosh. So we have Arthur on one side that takes all the responsibility and the other Merlin who wants to sacrifice for his king - for it is his personal mission."
*
Dan's Media Digest: "The concluding episode of "The Darkest Hour" premiere wasn't a huge improvement over last week's disappointment, but like most Part 2's it benefitted from having some resolution. However, with hindsight, this story didn't deserve a two-part treatment, as everything prior to the climactic moment of "Part Two" could have been cut from the overall story without any major loss."
Den Of Geek: "Julian Jones has set the bar incredibly high for the rest of the season with this two part story. Action is balanced with emotion as the stall is laid out for what could be a hugely satisfying battle between good and evil, with the delicious madness of Morgana going up against the virtue of Arthur and the Knights of Camelot."
Dork Adore: "Well, my worry that everything would get reset to basics didn’t come to pass. There aren’t any more major changes here (mostly), but the new age of Arthur as Big Man On Camelot is here to stay. Similarly, Morgana has been reinvented as an underground Rita Repulsa-styled supervillain."
SciFiPulse: "After last weeks opening episode I still find it somewhat brave of the writers to put Merlin’s life in jeopardy so early in the new series, but as this episode unfolds we do get a good idea to their reasons for doing so."
Daemon's TV: "After last week’s stellar premiere, this episode was a solid, if unspectacular, instalment...Much of the rest of the episode was fine and entertaining - I was never bored watching the show. I just wish that the character development we’ve gotten in past episodes had been on hand here."
SFX: "With all the camping and cross-country walking it’s like the knights are trying out for their Duke Of Edinburgh award; part one over-did the jump-scares and screaming ghosts, but it at least gave the episode character whereas, although it redeems itself later, this episode flounders at first, taking a good 20 minutes to find its direction. There are character moments here that are genuinely touching, though."
Geek Syndicate: "This week’s episode opens with a quick recap of last week’s thrilling premiere and chilling ending - Merlin seemingly sacrificing himself to save Arthur’s life once more and the prince struggles to say goodbye. But that’s not the only problem Arthur and his Knights have - the veil between the worlds is still wide open allowing the Dorocha to continue wreaking havoc all across the land. The only way to close it? Someone’s has to die - but who will it be?"
Digital Spy: Part two of 'The Darkest Hour' is another strong episode of Merlin - the show's cast excel throughout, but kudos in particular on that moving ending.