It's not a terrible game, but it's pretty much an inferior L4D clone in every aspects. The game looks decent and the gunplay itself is fine, but everything else is subpar and forgettable.
Levels are very generic and boring. There are no fun and exciting settings like in the L4D games. No Thrash Metal concert, no airport, no roller coasters, no Mardi Gras parade... just some generic streets, warehouses and other unimaginative locations. The atmosphere is also pretty dull and doesn't even feel like a horror game.
Special zombies have some very generic designs, and they are very bullet sponge-y and tedious to fight.
No gore effects, no memorable music, no mod support... but plenty of micro-transactions.

I'm sure you can have some fun with friends, but honestly you should just replay L4D 1&2 instead.