The TF2 Halloween event this year is one of the greatest things I've ever played. Part of it is I always have loved the boss fights in TF2, and part of it is Valve's sense of humor and how much they actually pay attention to their fans.

Here's a beautiful video detailing all of his new lines for the new map, his costume, and Zombie Heavy: http://youtu.be/AuB5XFqW5PE