For all the hype surrounding this game as the spiritual successor to Left 4 Dead, Turtle Rock's previous work, it hardly lives up to even a fraction of it. Which is a shame as even by the name it was clear that the developers were trying to evoke their past success to fuel their new project.
Let's get to the elephant in the room and talk about pricing. It is egregious. While most AAA games retail for $60 USD, this game hardly comes close to being worth that price tag. Singleplayer has all rewards disabled, the game has virtually no modding support, the pvp modes are highly limited not including a versus campaign mode as compared to their predecessors and more. I would say the game would more fairly retail for $35-$40 USD. There is also the matter of the disgusting $40 USD annual DLC pass they released alongside it. Time will tell if that is worth it's dollar value, but as it stands right now the developers are asking you to trust them and drop $60-$100 USD and that is before talking about the games special editions that only go up in price from there.
Aside from price the game has no mod support or mod functionality. For most modern gamers this may be confusing as to why this is a problem but it goes back to their previous work L4D, the game which they even named their game to remind you of (B4B). The L4D games, especially L4D2, had outstanding modding support. The game still lives on as strong as it does today thanks to fanmade character skins and maps, giving new life to the game as it gets older. B4B's deliberate choice to not include fan-creation tools shows they don't want fans making campaigns and cosmetics for free, but instead buy them from them or buy their $40 pass.
Beyond comparisons to L4D however, I personally felt in my time playing that the game didn't stand up on it's own legs. While the gunplay was smooth and satisfying and the graphics were fantastic the game is plagued with desync bugs and a rarity system which makes weapon choice more arbitrary instead of playing the guns you enjoy. Why use that SMG you enjoy when you just found an Epic quality shotgun that does more damage?
The perk card system is 50/50 in my view. It has a lot of potential and can be used to have some amazing gameplay experiences. But with how the system is implemented and how punishing the higher difficulties can be at some points spawning so many high tier specials as to wipe groups immediately there are now 'meta' perks you need to take at higher levels of play to be able to complete campaigns. Though I understand this is the issue when difficulty meets any customization mechanic, a 'meta' will always emerge.
All in all, if you are just in it for the gunplay and shooting zombie-like mutants and you don't mind spending the $60 then you can get B4B. For me, the value proposition just isn't there, not until the game is at least on a 50% off steam sale.