Even if the theme was something I absolutely cannot stand, the core mechanisms are so strong I'd still invest most of my money in collecting for it. It's pretty much the only real narrative driven card game on the market, and not in the sense that it's based on a story but rather you're actually experiencing a story unravel with multiple paths and choices made that can drastically alter the course of said story. It also has some of the most potential for growth and extension mechanically I've seen in a game in years.
It's somewhat similar to the Legacy games that have been coming out lately, only you don't really modify the board (or cards in this case) permanently. Even if you play the same story over and over again, things are always somewhat different AT LEAST, and drastically different otherwise. And while you can lose in the game, because of the narrative nature of the game it still rewards you with story content and other things that makes that experience unique to others.
Also, it's all co-op! There's no meta-game to worry about, and deckbuilding isn't strictly "put all the best stuff" because "best stuff" is different depending on the scenario you're playing. The game rewards you for your success, punishes you for your failures, and gives a little bit of melancholic nuance for whatever is in the middle. But no matter what, you can still play till the end.
*also, deckbuilding is quick and easy. It functions the same as Hearthstone. it isn't that intimidating as it can be in some other games.
Short answer: it's really freaking fun.