Jesus christ what a mess. Feels like it tried too hard to cash in on the Halo popularity craze and forgot to be a decent Red Faction sequel in the first place. Levels feel all gimmicky and rely on every hated console trend of the time, vehicle sections, turret sections, literal shooting galleries etc. Just buy the first game instead and install DashFaction for it, you'll have a better time with it, unless you want a monotonous slog with an occasional unintentionally funny mixed in between boring gunplay with abysmal level design and weapons.
Manage Installation > Configure > Tick Paradise Lost on Installation, let it download. Otherwise the DLC itself is great fanservice to Postal fans and somewhat of a redemption after the fiasco that was Postal III, lots of new fun features and the map makes good use of testing veteran players map knowledge.