The first DLC pack for https://www.trueachievements.com/Bulletstorm-xbox-360.htm
(originally announced back in February) has hit the Marketplace today, available now for 800 MSP. The Games for Windows Live version of the DLC has also been released for the PC version of the game.
Oddly enough, no date had been confirmed for the content, so its release today is a nice surprise! The Gun Sonata
pack adds five new maps and two Leash attachments. Two of the maps are for the Echo mode, offering brand new challenges in Crash Site and Guns of Stygia, while the other three (Sewers of Stygia, Hotel Elysium and Villa) are exclusive to the Anarchy mode.Here's a download link
for the Gun Sonata DLC on the Xbox.com Marketplace, and here's another
for the GFWL version.
As a side note, comparing the DLC achievements between the two versions of the game, you'll notice that Bulletstorm (PC)
includes five more achievements than the 360 version, essentially confirming a second pack of DLC for the game, and the five additional maps it will include - Mean Street, Mini City, Monorail Factory, Rock Quarry and Ulysses. Expect to see more details about this as-yet-unannounced second DLC pack soon!