Non-spoiler review: I was a kickstarter backer and rode the long wait for this game to see the light of day, and it was absolutely worth it. This is one of the best story-driven RPGs I've ever ran. The book recommends swapping GMs for the 4 parts, but I ended up running the whole thing for my group based on how we play (long 10-hour sessions once every three months), and it worked out really well - we're a seasoned group of CoC players and had a blast with this game.
The less the players know about this game going in, the better. There's a big reveal at the end of Act 2 that's best not spoiled, so if you plan on playing in this game, I recommend you don't read the entire book (or any spoilery reviews).
The story / narrative is the game's strongest point. It works perfectly with the fugue system, where you build your characters by having "flashbacks" to remember them doing things - for example, someone might approach you with a knife, and you have a flashback to being a knife fighter - so now "knife fighting" is a skill you have. The flashbacks also serve to help build your character's backstory, and eventually the backstory of the entire group, for a fresh take on the whole idea of bonds and connections.
The conflict resolution system is a modified version of blackjack played with a tarot deck. It works pretty well, especially once you're used to it - the game recommends using the imagery on the cards to help narrate what you're doing, but we ended up just kind of making our own stuff up as we went, and it worked out just fine. The first combat is designed to get everyone up to speed on how it works, but I highly recommend the GM run some mock combats before the first session to famliarize themselves with how it works.
All in all, Alas Vegas is a stunning self-contained game with a heck of a narrative punch. My group ran it in two 10-hour sessions. I highly recommend this game for a unique, one-or-two-or-four-off game that will leave your group talking about it for weeks afterward.