The DLC was ok but didn't really add anything to the main campaign. I've played through DI and DIR a couple of times, now I've got Sam B basically maxed out with all the best ("gold") modded weapons and $$$ (3M and counting ATM), I just roam all over the map killing zombies at will. It's best to attack hordes with explosives (the sonic grenade is the most effective) before they even see you, firearms are very effective at medium-close range against all comers especially when modded with fire/shocks, and the auto sniper-rifle at a distance. The melee weapons are the most fun and can be effective against hordes provided you don't let yourself get surrounded, and have space to back up. Oh yeah, indoors (warehouses, basements etc) where you are more likely to encounter mixed hordes of zombies, thugs and worse, you can kill many through the bars with firearms, open doors and toss in grenades and molotovs then close the door. Always carry huge supplies of explosives.