 Michelle Erica Green watched the episode for TrekNation, saying that it "focused far more on the characters and the consequences of their contact with their descendants than it is on the vast technobabble resulting in a successful traverse of the Xindi corridor". She praised David Andrews as Lorian, calling it "a wonderful bit of casting", and felt that the character's actions mirrored those of Captain Archer previously in the series. She compared the resolution of "E ²" to the Star Trek: Voyager episode "Deadlock" and the series finale of Star Trek: The Next Generation, "All Good Things ...". She felt that the lack of conclusion to what happened to the future Enterprise was "very satisfying". Jamahl Epsicokhan on his website Jammer's Reviews, called the episode an "acceptable but all-too-familiar time-travel concept" and a "step down" compared to the previous three episodes of the series. He compared it to the Star Trek: Deep Space Nine episode "Children of Time", which he said "was a far superior episode because it was about our characters — astonishingly and agonizingly — choosing one destiny over another, and sacrificing a great deal in coming to that decision." He gave "E ²" a rating of two and a half out of four.
