It's an okay game, but my L4D2 crew and I got tired of it pretty quickly.
Why it will never be a L4D2 replacement is due to the fact that it has no mod support. Custom maps are what has kept L4D2 alive and fresh all these years. There are thousands of excellent custom campaigns out there, and we've played them all several times. And people are still making new ones.
"When stupidity is considered patriotism, it is unsafe to be intelligent." - Isaac Asimov