Her voice blows you away one second while the next it breaks with vulnerability, most noticeably on This Is Acting's lead single Alive, a song initially written for Adele and then offered to Rihanna.
Knowing that this album is mostly made up of songs written forand rejected by other singers, you have to accept that perhaps it is a compilation of also-rans that aren't quite good enough.
That said, Sia's such a good writer, this collection of "rejects" stands up well, even if her "acting" as other singers means we at times lose sight of the real star.
The catchy dance track Move Your Body could just as easily be Florence, while there's a good level of fun and funk throughout on tracks including House on Fire and the Sisqo-sampling Sweet Design.
The standout song is One Million Bullets, perhaps not surprisingly the only one not written for another artist.
A sweeping, dark epic of a pop song, it showcases the highs and lows of Sia's vocal range and hits you with an emotional punch, like all the greatest love songs do.
