From the news page:
"In Only War, each player takes the role of a Guardsman, a member of the Imperial Guard and one of the countless billions of hardened conscripts constantly fighting on myriad fronts at the whim of the Adeptus Terra. In control of this martial alter ego, players go forth at the behest of their officers to fight the eternal and implacable foes of the Imperium – the foul xenos, the mutant, the heretic, and the dark forces of the Ruinous Powers."My initial thoughts are mixed. The setting chosen is the closest yet to tabletop Warhammer 40K and probably the most restrictive in terms of 40K background. Presumably you won't have to spend half a session digging latrines or standing sentry, but if you're away fighting xenos or heretics on your own, then I'd rather play Dark Heresy or Rogue Trader. On the other hand, the setting could offer a lot of opportunities the other games struggle to offer ***cough*** vehicle rules ***cough***
As part of the build up, FFG have put up Eleventh Hour, a starter adventure, here. It looks a fairly by the numbers affair, and I can't really find any signs of what makes Only War unique, but there are a few nice touches in there. Regardless, it goes without saying that I'll pick up the full book on release, Amazon are already offering it at a decent discount!