The hellgates are open, as now you can try Diablo III—absolutely FREE—on Xbox 360, PS3, PC or Macintosh:
Each of these options allows you to play Diablo III for free up to the Skeleton King in Act I, so if you've been looking to try out the game for the first time, or even to just get a feel for the controls on a new platform—your hour has come.
Unfortunately, the Diablo III demo is not available on Xbox One or PS4, however if you'd like to purchase the full game on next-gen console, you can do so here.
If you're looking for more info on any of these free editions of Diablo III, you can check out the full Console Demo FAQ here or the PC/MAC Starter Edition FAQ here.