I thought we were gonna COOL his HOT heart with a COOL island song.
Cold, Cold Heart is like Batman: Arkham Origins in that, even if we could have done just fine without it, it's a good enough excuse to go Batman-ing around town for a few hours.
I mean, sure, it's pretty far from a master-class in DLC packs. It's almost entirely linear: the "open world" doesn't appear until halfway through, is limited to two of the main game's nine districts, and has only a small handful of side-activities (which are even less narratively meaningful than those in Arkham Origins). It glosses over the question of "What ability upgrades did the player already get?" by unlocking everything from the main game -- except, hilariously, the Glue Grenade. There's only one "new" upgrade, with minimal effects; after a few hours of build-up, Batman's new suit has the same general characteristics as his old one. And Mr. Freeze was already in the last game, so we're not exactly covering new ground here.
Like, by the numbers, this would be a phoned-in expansion. But it succeeds in the same way that Arkham Origins did: by providing exciting combat and stealth sequences, in the spirit of the Arkham franchise. It may not be innovative, and it may not be smart, but it works.
Case in point: the story begins with you playing as Bruce Wayne, and Mr. Freeze invades your dinner party, so you beat the living shit out of his gang while Alfred keeps your dinner guests distracted in the other room. Thrilling set-up! But... you're still Batman, so you don't kill the gang members, you just knock them out. Cold, Cold Heart is a success because it moves quickly enough to prevent you from considering what those guys will say about Bruce Wayne when they wake up.
It's kinda dumb, but it's still fun.
Better than: Deus Ex: Human Revolution - The Missing Link
Not as good as: Deus Ex: Mankind Divided - System Rift
It's been a while, but maybe comparable to: Batman: Arkham City - Harley Quinn's Revenge
Progress: Finished the story, did like ... half? of the optional stuff.