I have to say that, though I do like the Sacrifice, it would be nice to see valve release a downloadable campaign which has more than three levels.
That being said it is always fun to find your way through for the first time.
Also, I got around to reading the sacrifice comic Valve has been spamming for a while and it is shite. The art is really well done but it sticks with zombie clichés the entire time. There is no real story just one thing happening after another. I was hoping for at least one character arc...
I think I like the original survivors less now that I read the comic.