i thoroughly enjoyed it, but i also play with friends. For me, it had some of the most intense firefights ive ever had against AI opponents in a first person shooter. That is not to say the AI is incredible, its actually rather simplistic, but whereas the individual AI classes are simple, they do work enough together that when combined with their damag sponge will require you to utilize tactics. Its the only shooter i can think of where 3 guys armed with machine guns and the latest tech in a fortified position at the end of a hallway will shit their pants in terror at the sight of 7 guys in hoodies armed with golf clubs. Unrealistic to be sure, but challenging never the less. A single shotgunner can and will rip through your whole team, causing you to preplan if a wave of shotgunners come after you.
This is all late game stuff though. While you are leveling up the game is easy enough. Ill go through some features next.
The underground, first expansion. Basically procedural created dungeons that give loot. Nothing exciting really, but does give a lot of loot.
Survival, second expansion. I love this mode. You and 20 some people are dropped onto a server instance of the map in random locations (keep in mind its a massive map, you will likely only see a handful of players the entire time). You start with basically no gear and a pistol. you are infected so you need to find medicine to buy some more time, and its cold outside so you have to find warm clothes. there is a freezing gauge, the better your clothes the slower it empties. Going near fire or going inside warms you up. You can kill enemies for loot, but many players die early from biting off more than they can chew. You can either find loot from enemies or chests, or find crafting materials to make your own. When players die, you can loot their stuff (so long as you play pve mode, you cant attack each other till you get to the Dark Zone. Oftentimes, you have to run or hide from enemies. Most players dont make it. The objective is to get to the Dark Zone (which is pvp enabled, and has more difficult enemies) and summon a helicopter to extract. Most successful runs take anywhere from 45-80 minutes, although people have lasted 2 hours (medicine has diminishing returns and will stabilize you for less and less time)
havent played the last expansion, dont even know if its out.
Also, stay out of the (non survival) dark zone unless you know what you are doing or you like to be griefed.