At the time, I just thought that it was kind of a fun title—a good working title to [remind myself to] be playful and not hold myself back.

[15] In a positive review, Tim Sendra of AllMusic called Extreme "both Nilsson's most interesting album and a striking reboot", citing her experimentation with "new moods" and "new genres".

[9] Jana-Maria Mayer of German Musikexpress characterized the album as a "romantic indictment of the Anthropocene" and praised Nilsson's songwriting.

[13] Sophia McDonald of Loud and Quiet, in a mixed-to-positive review, considered Extreme "an LP that is generally surprising in its trajectory" and noted its "nostalgic fun", but criticized it for a lack of "closeness" and "intimacy" to Nilsson in comparison with earlier works.

[11] The closing track "Pompeii" was highlighted by Raphael Helfand of The Fader as a "happy-sad classic" that serves as a "rallying cry for resilience in the face of impossible odds".