 Publisher 's Weekly said , " It is a testament to the storytelling that the existence of this parallel world and the convergence of Peter and Thea 's stories , told in separate chapters , are both credible and absorbing . Young readers will find this a journey worth taking . " Kirkus Reviews found the novel to be a " <unk> enjoyable <unk> adventure " , praising how the adventure tests the main characters ' courage as they learn the truth of both worlds . <unk> Smith from Horn Book Magazine found the two main characters well written and the city of Gracehope well structured . While , Smith found the city 's origin unbelievable , she recognized that few people would care about that and compared the threat in First Light similar to the one in The City of <unk> . <unk> Hubert from <unk> also compared the novel to The City of <unk> and to Neal <unk> 's <unk> . Hubert criticized the slow beginning and flaws in the mythology and structure of the underground world , but still felt that " the icy setting and global @-@ warming theme are well realized " . 
