[2] Due to HIM's minimal studio experience, producer Hiili Hiilesmaa played a key role in honing the band's sound, and was touted as the honorary sixth member of the group by vocalist Ville Valo.

[5] The track also featured guest vocals by Sanna-June Hyde, an old school friend of Valo's and guitarist Linde Lindström's ex-girlfriend.

[6] Valo had originally envisioned the album's front cover as featuring a replica of his body that would slowly turn into a skeleton as it went down.

[7] Due to minimal funds and time constraints, the band were unable to fulfill this idea, instead opting for a more traditional photo session with Vertti Teräsvuori.

[7] The finished cover art was meant as a combination of goth and eroticism with its dark red color scheme, while Valo posing was described as a "Jeanne d’Arc -style tortured figure".

[7] BMG were not fond of the finished artwork, feeling that it evoked too much of a "Billy Idol vibe" by just having one band member on the cover.

666 has been described as a combination of heavy metal and 1980s rock and goth music, with Valo citing Type O Negative as the main influence on the album.

[10][11] Lyrically the material is heavy on symbolism centered around love and death, a theme that would continue through the band's later work as well.

"[4] The album opens with "For You", which features a '50s-style guitar intro, inspired by Chris Isaak's "Wicked Game",[12] while the main riff of the song is taken from "Bloody Hammer" by Roky Erickson.

[12] "When Love and Death Embrace" was chosen as the first single from the album by BMG Finland's Asko Kallonen, who felt that the song "represented HIM at its core",[6] to which Valo agreed, touting it as being a good representation of the band overall.

[13] The banging sounds featured on "The Beginning of the End" were achieved by the band hitting trash bins in a cellar, while the opening riff was performed by Valo, as Lindström was not present at the studio and the band wanted "the world's shittiest sound played badly", which they believed Lindström could not provide.

[18] "(Don't Fear) The Reaper" was originally released by American rock band Blue Öyster Cult on their 1976 album Agents of Fortune.

[22] On the day of the album's release, HIM held a party at King's Kakadu, a strip club in Helsinki, where they performed three songs by Rauli "Badding" Somerjoki, dressed in suits with slicked-back hair, as well as '50s-style instruments.

[24] "Your Sweet Six Six Six" and "Wicked Game" were released as the follow-up singles from the album, with the former charting at number nine in Finland and the latter receiving a music video, directed by Markus Walter.

[31] After returning to Finland, HIM also decided to part ways with drummer Juhana "Pätkä" Rantala, who was replaced by Mika "Gas Lipstick" Karppinen before the start of another German tour.

[1] Rumba's Johanna Kiiski also gave the album nine out of ten, describing it as delivering on all expectations set-up by 666 Ways to Love: Prologue.

[10] Ravelin concluded his review by stating that the album "succeeds in pleasing everyone, whether they're into rock or pop", and singled out "It's All Tears (Drown in This Love)" and "The Beginning of the End" as particular highlights.

666, and called it "a first-timer's endearing virginal exploration", stating: "First you're ashamed of it for a couple of years, then you understand its good parts".