My buddies and I spent a few nights playing and here's my overall impression. The graphics and animation are poor, but adequate - if you come from Minecraft they are a step up and if you come from L4D they are quite a step down. For instance, if something kills you there is no dying animation, it shows you just standing there as the camera pulls away in 3rd person. You'll frequently take damage from a variety of things, and it all shows as blood splatter on your HUD, even if its just periodic health damage from frostbite. Sometimes it can be hard to figure out what damaged you until you can decipher the status icons in the HUD. Playing single player is very challenging and quite random, at least under default settings. My first spawn was in some Arctic area where I proceeded to freeze to death; my last SP play, I spawned in a perfect area and went almost 18 hours (in-game) without a single hostile crossing my path. You have to play quite cautious and juggle a lot of survival issues - core temperature, hydration, food, health, stamina, tool quality. Running all over the place like a typical video game character got me a sprained ankle quite quickly, when I stumbled over the edge of a small embankment. At first I rolled my eyes at what seemed like a trivial fall, but I had to acknowledge that it is probably what would've happened in real life. Oh, and I died from dysentery, and had a laugh remembering the last time I died from dysentery in a video game: 30+ years ago playing the original 'Oregon Trail'.
Rough edges aside, it is addicting once you get the hang of it, and it got really fun when my buddies got together and we MP'd it. The first day was spent trekking across the map to find each other, and in the process two guys found a very defensible house which we made both our meet-up spot and fort. One guy spawned miles away, so I spent most of my time gathering clothes and weapons for him while he ran and sneaked across the countryside, defenseless, to come join us. Once he found me in late afternoon, I equipped him and he continued on to the fort - but we realized we had no food whatsoever. So while they fixed up the house, I spent the remaining daylight hunting - and got caught out after dark. I spent a harrowing time running back to the house with zombies following, at full speed, in my wake, tracking me by the scent of all the fresh meat I was carrying. The game does a good job of making nighttime something to fear - shambling zombies become full-speed, and untiring, and it is truly dark. They can be tricky to kill in daytime, but at night in darkness and running at full speed they are very tough. I arrived at the house with only moments to spare, and my buddies helped put my hunters down. From there we had a blast more or less nest-building our fort. Survival chores can be split up, I spent my daytime hunting for more food, two of the guys went to explore the nearby town, and the last guy worked on the house. After three hours of play, we made it to the 2nd arrival of night, with five deaths among us (mostly from the one guy that kept spawning miles away from us, in terrible biomes). The MP game could be laggy at times and sometimes had glitches where objects became invisible (particularly annoying running into invisible saguaros), but was overall fine for four people and was quite easy to set up within Steam.
We paid half-price for it ($10 I think). The game is not polished, and doesn't feel terribly deep for a sandbox, but I think there is enough gameplay left in it that I am happy with the purchase even from a SP standpoint. From a MP standpoint, a 4 player co-op that we can happily sink many hours into is pretty much priceless, so more than happy there. I have my doubts how long the game will last before we get bored; but the random world design ensures it is a game we can likely return to periodically when we get the itch.