I hate these fucking fire wolves
No, The Frozen Wilds didn't wrap up Horizon's cliffhanger ending. I guess they're saving that for a sequel.
Overall, Frozen Wilds is more of the same Horizon stuff, but smaller: a main story, some side quests, some collectibles, and a few new weapons and enemies.
A side quest in The Frozen Wilds unlocks modification sockets for the spear weapon. You can find and collect spear mods during the main game - and I found several - but there's no way to use them until doing this quest. Huh.
The main quest line is relatively short, and the story focuses a little more on its characters' personal growth than the main game's story did. Otherwise, it feels a lot like a subset of Horizon's story: the plot is basically the same, the technological details are the same, and the themes are extremely similar. It's a bit disappointing that, narratively speaking, this expansion adds so little to the game.
It doesn't add much to the gameplay, either. Except frustration with the new enemies. Particularly the Scorcher, a wolf-styled machine that can leap across the whole damn map and can attack like a billion times a second.
In the main game, I hated when evading multiple attackers gave me precious little time to counterattack. But with the new enemy types in The Frozen Wilds, solo attackers have the same effect; it feels close to impossible to fight back. And unlike most of Horizon's high-threat machines, which have big glowy components that can be removed or destroyed to make them substantially less dangerous -- the fucking fire wolves never stop with their pouncing and slashing and flamethrowing.
In a broader sense, those fuckers - and to a lesser extent, also the new bear-type machines - feel like a misstep in Horizon's combat design. Most of the main game's enemies set a pretty good precedent for teaching me what weapons to use, and what components to target; I became better at fighting them by developing those techniques. The wolves are less vulnerable and less complex; all I learned from fighting them was how to roll away.
But I digress. I didn't have to fight very many of those fucking fire wolves, so I can't begrudge The Frozen Wilds too much for having them.
What I will begrudge it, a little, is not pushing the envelope more -- especially with its storytelling. The Firebreak backstory was entertaining, but didn't reveal anything about the "metal world" that I didn't already know from the main game.
The Frozen Wilds is worthwhile, but I don't think it quite meets the quality bar set by the main game.
Better than: Grand Theft Auto IV: The Lost and Damned
Not as good as: Grand Theft Auto IV: The Ballad of Gay Tony
While most of Horizon's backstory is well-researched and believable: the idea that real scientists would do a node-rotating puzzle for security clearance is pretty silly.