Well, it looks like a demo will never come out for this online-only game. SCEA responded to GameDaily BIZ: "Warhawk was designed to support up to 32-players online simultaneously. In a demo version of a multiplayer only game, there is little control over how many players will be on a dedicated server at a time, potentially leading to smaller online battles that do not fully do justice to the title's fast combat and frantic play. Additionally, Warhawk development underwent an extensive beta trial that included nearly 10,000 participants, which offered a wide audience ample opportunity to experience the game and provide valuable feedback to during Warhawk's development."
So, it looks like the beta was the only free chance you had at the game. You're just going to have to trust us: Warhawk is good, and you will like it (provided you can actually sign in on firmware 1.92 ... )