On first impression, this reminded me of nothing so much as mid-period Bowie - it's the voice (scratchy, harangue-y, fraught and declamatory, etc) that furnishes the initial grounds for the comparison, but further listening disclosed a similar electric guitar rock 'n' roll/power-pop quasi-space-age (though more Hunky Dory or even Heroes than Ziggy) drama thing going on. It ain't derivative, though - Streethawk is quality indie-pop with intimations of the epic, impressively free of standard progressions and structures while remaining strongly melodic and catchy, and distinctively au courant while also seeming to draw inspiration from classic singer-songwriters of the 70s and 80s (including, dare I say it, Elton John - just check out some of those extended piano breaks!).
I don't really know the story behind Destroyer, but I read somewhere that it's basically the project of Dan Bejar, one of the New Pornographers band members and songwriters (which certainly sounds right). This kind of stuff can sometimes leave me a bit cold (I generally only like every second NPs song or so - though "Mass Romantic" and "Testament To Youth In Verse" still get me between the eyes pretty regularly - and the whole AC Newman thing completely passed me by) but there's something to Streethawk that wins me over - it's quirky, sure, but also seems to have a soul and a substance to it. Anyhow, faves probably "The Bad Arts" and "The Crossover" at the moment.