I saw a lot of comments/chats today from my fellow Warzone/Rebirth players that DMZ feels too slow and didn't have enough action, but the reality is, DMZ is meant to be more slow and tactical. That's not going to appeal to everyone, but if you tackle multiple missions each raid, you can keep yourself occupied.
I'm hesitant to say Call of Duty should add MORE players/PvP because if you were a solo and tried to complete some of these missions, it would be difficult unless you had decent loot. I played for 8+ hours today and enjoyed it quite a bit. A different pace, but that's not bad, and when Warzone is out, you could always switch between the two for variety