Upon release, Mantaray was well received by critics, with praise focused on Siouxsie's voice and the different compositional styles.

Commenting on the news on her website in July 2006, Siouxsie stated, "At least I didn't have to get someone spray-painting my name on the front of the Universal building"!

[4] It was a reference to a famous episode which took place in early 1978 in London when record companies had been tagged one morning with the command, "Sign the Banshees, do it now".

Evans and Jones together composed the music for the tracks "About to Happen", "If It Doesn't Kill You", "Sea of Tranquility", "They Follow You" and "Heaven and Alchemy".

Instead of recording the album in one block session, she commuted from France to Bath in England where was located the producers' studio.

In addition to the standard jewel case and a tri-fold Digipak, Mantaray was also released on vinyl in both countries.

[18] Concerning the quality of the songs, journalist Charlotte Heathcote noted, "Impressively, there's not a let-down track on the album and a perfectionist attention to detail sees synths, strings, wind and percussion used to creative, compelling effect".

[24] Simon Price in The Independent shared the same point of view, stating that "Mantaray is a bracing and beautiful blast of ice".

[26] Q's Gary Mulholland published a positive review and said, "Siouxsie voice is as rich and sensual as ever, and lyrical references to rebirth abound".

[22] In a review rated 4 out of 5 stars, Metro commented that the 10 songs of her first solo album "do add further depth to her repertoire".

[16] Slant Magazine qualified Mantaray's sound as "distinctly modern", stating that "it's Siouxsie voice—trembling and echoing all at once—that reaffirms the album's urgency".

Reviewer Dan Cairns praised the music, writing: "its mix of lush, Bernard Herrmann-like strings, Bond-theme melodrama... make a fitting soundbed for that imperious, distinctive voice".