Regarding The Passing DLC, here's what the company had to say:
Revealed back in December 2009, The Passing will see survivors from the first Left 4 Dead meeting up with the group from L4D2. About a month after The Passing is released for Left 4 Dead 2, the original L4D will get new content detailing the journey taken by Bill, Zoey, Louis, and Francis to meet up with the cast of L4D2.
Was that a typo? Game Modes? Didn't we mean Game MODE? Did we mean to include that 'S'?!?!?"
- A Wicked Witch Bride!
- A Gargantuan M60!
- A Slashing Golf Club!
- And Introducing The Fallen Survivor!
- Meet 3 Left 4 Dead 1 Survivors!
- New Game Modes!
YES WE DID!
Good game, would buy again. Also at half price and with all the DLC available (or soon to be) for this game there is no reason not to have it now.