I've been enjoying the game a lot, though still haven't finished because I've only been playing when my coop partner is around, and he's got a weird work schedule.
This first DLC is like... 10 minutes of content I'd guess? It's 2 quarantine zones for $5. For those who haven't played, there are areas on the map marked as quarantine zones, where the zombies got in and the place was barricaded off with the zombies still inside. You go up to the door and load into an interior area where you have to collect 5 boxes of supplies, and whatever other loot you might see laying around. I don't think a quarantine zone has ever taken us more than 5 minutes, and usually they're less than that. So you get 2 of these, for $5.
The second one, the Ultimate Survival Bundle, sounds like it's only weapons blueprints and outfits. So you get a couple new variations on "do more dmg with this weapons by adding fire/electricity/poison to it", and a couple outfits that are only ever seen by coop partners.
The third one could be alright, depending on how fleshed out it is. Sounds basically like horde mode.