Man that's a tough question to answer. It's brutally unforgiving, has permadeath, pvp, hunger/thirst mechanics, HUGE 225 sq. map, and of course ZOMBIES ( 28 days later style- fast ). It takes some time to get used to all the diff mechanics, all the while trying to evade Z's, players, and trying to scavenge enough equipment to survive ( weapons, food, water ). There are also cars, trucks, bikes, and even a chopper in the game, that need to be repaired and fueled to get running.
This game has give me some of the most tense gaming moments I have ever had. Crawling around an airfield to get some high end loot for over an hour, trying not to aggro a Z, and praying a sniper isn't hiding ready to pick you off, is such a unique combo that just elevates the gameplay. You NEVER know when your going to get into a gunfight. Your first instinct is to clear the area of Z's, but in doing that, you notify any players in the area that there are players nearby. The way the game is now, most players will kill on sight, as it's so hard to trust a random to not kill you for your loot.
My advice is watch some vids, check out the surprise bus ride recruitment. A great example of the games uniqueness. Also, don't expect to play this like COD or BF. there will be times when all you do is run or crawl for a significant time, remember its a 225sq ft map, all in real time. I haven't tried yet but I'm sure it takes about 1hr to go from one side to the other running the whole time.