It's nothing more than a worse L4D imho. Graphics are not that pleasing/not up to date and it doesn't have the same spooky/dense atmosphere that L4D managed to create. The defensive parts with "building" stuff is cool, but nothing really new.
If you get it, make sure that your friends get it as well as it's hella boring solo.
I will refund it, though. It's just not worth 35 Euros on Epic's storefront. I'll happily take it for 20, but I'll see if I can get it around that price from another keyseller.