Redbadge
Explorer
If spell slots are what power their spells, they really don't have a lot of casting per day. Obviously, the slots will scale with the "Slot Level" column. So warlocks will have 2 5th level spells per day. Similar top level power to full casters, but none of the depth.
As the "encounter-based" class, Warlock's spell slots likely all recharge during a short rest.