 The Guardian published three reviews of the episode . Sam Wollaston gave the episode a positive review ; he thought it was a " wonderful episode " that " would be hard to top " . Wollaston joked in his review about Richard Dawkins 's cameo , and compared his anti @-@ theological mannerisms to the Daleks . Gareth McLean described the end of the episode as a " genuine , jaw @-@ dropping , outta @-@ nowhere cliffhanger " . He commended the production team for successfully suppressing information about the regeneration in an industry often stifled by leaks . Stephen Brook of The Guardian 's media blog <unk> , thought the episode was " unbelievably good " and " genuinely scary and exciting " . He theorised about the questionable regeneration : whether it was genuine and , if so , who would portray the next incarnation of the Doctor ; and which companion will die in " Journey 's End " . 
