 The episode has received critical acclaim from critics . Dan Martin of The Guardian said that it contained " the series ' most tearjerking <unk> so far " and the " psychedelic premise [ gave ] the characters the chance to shine " . He praised Karen Gillan 's difference in performance as the old Amy and her improvement in performance since the previous series . Martin later called it a " damn near perfect episode " , rating it the best episode of the series , though the finale was not included in the list . Gavin Fuller of The Daily Telegraph gave the episode four out of five stars , praising MacRae 's ability to overcome budget issues and deliver " quite a powerful and moving drama , with an ending that although inevitable still delivered a well of sadness " . He thought the older Amy 's " technical wizardry seemed a tad unlikely " ( she manages to scrounge up a sonic screwdriver while waiting for the Doctor ) but " the power of Gillan 's performance skated over any minor quibbles " . 
