So I've played for about 40 hours now, here's my take on it (TL;DR at the end):
First of all to whoever thinks you need to spend money for inventory slots: You're a moron. Items stack with themselves except for equipment and trade goods, each item takes one slot and you get like 25 of them in the first 2-3 hours of gameplay. Vendors are on literally every other corner and apart from getting money you don't really need any of the dropped items anyway except for very rare materials. You also have storage in every major and minor city (which is not shared).
The game world and its content is quite large, I'd actually say its fucking huge and the sheer amount of quests will overwhelm you. It is for all intents and purposes a sandbox MMO, in the truest sense. If you suffer from OCD or want to 100% the content, its gonna take years. Literally.
The whole concept already manifests itself when you look at how the levelling progession goes. Very few quests actually grant XP, most of them rewarding you with some other kind of "currency". 99% of the experience you gain will be by killing mobs. Doing so during night (each day lasts 4 hours realtime) will increase the XP gained by 200% but the monsters will also hit harder. Up until level 50 it will take about 30minutes to an hour of pure grinding per level up. Once you hit 50 it will take about 15-20hours of pure grinding to gain one level. If you die, you lose a huge chunk of XP, so dying is a no-no if you want to actually progress past 50. This goes on until around level 55, once you hit that it would take a couple of weeks/months to even gain a single level, at least with the content currently available. Gear has no requirement so none of this really matters all too much except for the level requirement of upgrading skills.
Apart from player XP there are three other major mechanics that you gain experience in that enhance your gameplay in certain ways: Skillpoints, Energy and Contribution. A short sumnmary on what each of them do:
Skills come in a variety of choices, most of which have multiple ranks. The combat is very fluent and based on chaning your abilities together so you can take advantage of back-attacks or knockdowns. I won't go into detail about the combat since you can just check it out on youtube/twitch if you feel like doing so. You get access to almost all skills at rank 1 before you hit level 20 and can earn skillpoints by doing quests, leveling up or simply grinding monsters. Every skill and the respective rank upgrades require you to have a certain level and also require skillpoints to be spent. By the time you hit lvl 50 you usually earn around 500 skill points which enables you to skill about a third of all possible skillranks. You usually stick to a bunch of spells/abilities you like and max them once they become available, eventually you can max all of them.
Energy is quite simple, it works similar to every generic browsergame energy mechanic. You gain one every 3 minutes on characters that are logged in, and one every 30 minutes when you are offline. You spend it on a lot of actions in game, be it gathering resources, investigating stuff for quests or hiring workers/processing materials etc.
Contribution is earned by doing quests and enables you to build your own little imperium. The world map is basically divided into a shitload of nodes which can be anything from towns, gathering spots or certain quest areas. You can "activate" these nodes by spending Contribution (and further enhance them by spending energy), which then gets reserved until you withdraw your contribution. Wanna build a trade route from one town to another? Link them via a bunch of smaller ones or you don't get any profit off of it. Want your workers to gather that iron-deposit? You will need to have all nodes linked from the node to whatever town your workers were hired in. Even buying workshops/lodgings for your workers require you to spend contribution, you can withdraw it whenver you want though.
Combat really is the weakest point of the game anyway. Most of the other stuff is done in a well thought-out sandbox. Crafting is mostly done by hiring workers that gather resources, refine those resources and eventually craft them into items. Some parts of this chain can be done by the player, but it costs energy to do so and workers are simply more efficient especially once they levelled up after doing these tasks for a while. To do any of this you will use your contribution and energy to set up your own manufacturing process. Hire a bunch of workers, provide them with lodgings, connect nodes for them to gather resources from, have them store these resources in the aforementioned storage, provide them with workshops. Every worker has a limited amount of tasks he can perform before he runs out of stamina, so will eventually have to refill his stamina. Doing so requires food/drinks which you can either buy or craft yourself. Which requires you to set up another chain of production, which requires more contribution/energy to start with etc. None of this is automated though, you can only set up a certain amount of queues but you will often have to micromanage this stuff. If you actually invest time into doing this you could easily sell the items on the market to make money. Some of the craftable items will still require materials that are only obtained by killing monsters (and refining these materials multiple times via the dozens of different processing options).
You can ofcourse forego all of this shit and just buy stuff off the auction house, which requires you to get a decent amount of cash. You can grind monsters, which will take a lot of time, craft shit and sell it or use the trade system that is in the game. Most major cities have a trade manager that sells certain trade items at a lower than base price, which you can sell in other cities for a profit. These weigh a shit ton though so you either carry them one by one which is really dumb, rent an NPC to transport it for you or just build your own caravan or ship to move it yourself. Wagons/Ships can carry a bunch of them and depending on the distance (you still need to connect all the nodes from one city to another via Contribution) you can make a considerable amount of cash each day. Your ships/transports can be attacked by bandits though, haven't had that happen to me yet so I cannot tell you how that works.
All of this basically means that if you want to be the best goddamn blacksmith on the server you don't really have to do a lot of grinding monsters. You can easily do that by staying level 20-30 and set up your trade/manufacturing emporium, there is so many goddamn quests that grant Contribution that you can easily get to 200+ in the first 20 levels. Want to breed horses all day every day? Go catch a bunch of tier1/2 horses, level them up by riding them around then breed them to gain higher tier horses and sell those for cash. Or go play farmville by buying seeds, growing them and harvesting them so you can either cook them into food to sell, eat yourself or just sell the raw materials or do whatever the fuck else you wanna to because you can. Watch a movie on the big screen while grinding monsters like a retarded maniac for hours straight because it is nighttime and do your crafting during the day.
TL;DR: All in all it is an actually well made sandbox especially for crafting/trading/dicking around, which obviously has a lot of flaws but the whole underlying system is really good. The reallife cash shop is bullshit and way too expensive but people still seem to spend money (I spent all my pre-order points on buying goddamn cats that meow at me every couple of seconds and loot shit so I dont have to press R 200 times a minute). The UI is horrible but once you get the hang of it it won't really bother you too much, it takes some time to get used to though. Upgrading gear/leveling up barely changes the way you look, you will run into hundreds of people that have the same basic look you do except for the part that you can change during character creation (which in itself is fucking ridiculous and could probably be licensed to any VR porn publisher). For 30 bucks I have already gotten my moneys worth and I have barely scratched the surface, I certainly did not expect to find a decent crafting/trading sim game in a korean MMO. Mechanics are convoluted as fuck though, explaining the whole amity system takes pages and pages of formulas and other shit alone. If anyone wants to check up on certain mechanics they can use
this guide, it is a little outdated but should be in depth enough to give anyone a general idea on how everything in this game works.