The main factor that makes this song different is a usage of electronic beats in the background. But not in a Nu Metal way, as was popular with the band on 2003's "Fallen", but more in an Electronica sort of way, which is heard in synthesizers and synth drum beats. Frontwoman Amy Lee stated that the new album is inspired by the likes of Depeche Mode, Massive Attack and MGMT, which is relatively obvious.
Otherwise, the single has the quality of a traditional Evanescence track, with heavy metal riffs, which expand on the feeling of hatred and bitterness of which the song seems to deal with, which is also found in Amy's powerful vocals. Violin and piano also appear in the songs arrangement, traditional of Evanescence. If there's one thing I would complain about, it's that I find Amy's repetition of the phrase "Do what you want-you want" to sound like something from a cheesy 80's pop song, which is quite annoying.
Other than this, "What You Want" is a slick and catchy goth rock song which serves as evidence that Evanescence have been evolving during their time out of the limelight.