"Lacrymosa" garnered generally positive reviews from music critics, who praised Lee's vocals and arrangement and deemed it one of the most memorable songs on The Open Door.
[12] Lee stated that she had always wanted to make Lacrimosa from Mozart's Requiem a metal song, and The Open Door was "the time for that, for trying things I hadn't been brave enough to try before.
[14] The Gauntlet writer Claire Colette said the song features a "violin intro, synth worth of a Nine Inch Nails album, and Omen-esque choral sections that are very haunting.
[18] John Hood from the Miami New Times opined that, thematically, "'Call Me When You're Sober' sent a man away, "Lacrymosa" kept him there, and "Cloud Nine" told the clueless dolt why he would no longer ever be welcomed back.
's Sam Law said that the title is a "take on the Latin term for "weeping"" and Lee's lyrics "evocatively revisit the tears shed in the years preceding.
"[20] In 2017, Lee and Campbell reworked "Lacrymosa" into a fully orchestral version with electronic percussion for Evanescence's fourth studio album, Synthesis.
[2] The New York Times's Kelefa Sanneh regarded the song as "grandiose even by the album's standards" and "an audacious, exhilarating blast" in which "Evanescence sounds huge".
[18] Claire Colette of The Gauntlet called it a "haunting" song,[15] USA Today's Edna Gundersen deemed it "wonderfully bombastic",[28] and Revolver's Zoe Camp dubbed it a "standout".
reviewer Nick Ruskell wrote that the classical parts and heavy guitars in the song "entwine perfectly to create a stunning Wagnerian wall of choir-led dark majesty".