Ever since Fantasy Flight Games announced an Arkham game in the LCG format I have been interested. I have had a load of fun playing Eldritch Horror and the idea of a more compact game in that vein and coop to boot was to good a concept to pass up. 
First things first, you should play this game without reading any spoilers at all. I am going to avoid them completely in my review and I suggest when you open your game that you do not look through all the scenario cards. Doing so will spoil some enjoyment of the game.
A game in full swing

Arkham Horror: The Card game is a fascinating mash up of LCG concepts with an RPG underlay. The deck you might build in a competitive game like Magic or Netrunner in this case represents the character you are going to take into the story that the game creates. This decks contain equipment you might use, allies you can call upon, spells to conjure and events to help you on your way. 
The scenarios are where this game gets really clever. In the core there are 3 scenarios making up a campaign called Night of the Zealots. Each scenario has an Act deck, which advances as the investigators make progress in the scenario, and an Agenda deck, which acts as clock for the machinations of the forces that plague the good people of Arkham. I can’t say too much without spoiling but the designers are already playing some very clever tricks with the space they have created. I was genuinely surprised by some of the moments during my playthrough of the campaign and I can’t say that about many games. 
An Encounter deck, made up of different sets of cards depending on the scenario, sets obstacles in the way of the investigators to be overcome, on top of anything the scenario throws at you. Finally there is the chaos bag which is made up of a number of tokens drawn to decide the outcome of the various tests you will encounter. 
Let’s visit the deckbuilding for a moment. Each investigator has their own rules for deckbuilding which is a neat trick in and of itself. However the cards you put in your deck at the start of the campaign are not the be all and end all of this process. As you advance through the campaign you gain experience depending on how well you do in a given scenario. This experience can be used to buy better versions of the cards in your decks or give you access to allies, equipment and other cards you didn’t have access to before. This is a fascinating series of choices that you are presented with in between scenarios, as you try and hone your deck to deal with the challenges ahead.
I have been immensely impressed with Arkham Horror: The Card Game. The rulebooks are some of the best that FFG have produced, and I would be the first to call them to task for such things. The designers have created a fascinating design space that they can now play with and they are already showing signs of having fun with that space. Arkham is a huge amount of fun, with emergent stories, great decisions and fascinating design philosophy behind it. A strong start for a game that I am sure will grow into something amazing.