"Metacritic" gave the episode a Metascore—a weighted average based on the impressions of a select twelve critical reviews—of 87. Robert Bianco of "USA Today" wrote that "returning with a heart-stopping, perfectly pitched episode ... "Lost" is an oasis in a strike-parched TV desert." Mary McNamara of the "Los Angeles Times" described "The Beginning of the End" as an "emotion-churning chemical dump right in the old brain stem—horror, hysteria, regret, adrenaline and what ... will happen next?" Adam Buckman of the "New York Post" gave the episode four out of four stars. Maureen Ryan of the "Chicago Tribune" "blissfully enjoyed every minute" and noted that "there aren't any faults". Diane Werts of "Newsday" raved the episode as "superb" and "insanely entertain[ing]" and concluded her review with ""Lost" seems to have found itself". Tim Goodman of the "San Francisco Chronicle" declared that it and "Confirmed Dead" "are roller coasters of fast action and revelation [that are] good to see". Matthew Gilbert of "The Boston Globe" pointed out that ""Lost" can still make the pulse race and the brain tingle ... [and] remains TV's most gripping serial". Alan Sepinwall of "The Star-Ledger" was unsure "if "Lost" is ever going to give satisfying answers to its many, many remaining mysteries ... but when it's as scary and hilarious and moving and exciting as these two episodes, I'm okay with that." In less positive reviews, Rodney Ho of "The Atlanta Journal-Constitution" called it "a satisfactory return episode with a fair share of drama and pathos ... [that] provides just enough revelations to keep fans hungry for more" and David Hinckley of the "Daily News" rated the episode with three stars out of a possible five. Brian Lowry of "Variety" said that ""Lost"'s return goes down like a welcome tonic as scripted TV fades to black ... providing an unusually generous array of juicy moments for the large (and, at times, neglected) cast." Mark Medley of the "National Post" called it "a brilliant season premiere" with multiple "jaw-dropping moments". Jeff Jensen of "Entertainment Weekly" felt that the premiere was mind-blowing and featured good acting by Garcia.