If you aren't expecting much you'll be pleasantly surprised--If you're expecting anything more; you'll be disapp
You have a hero character and up to 8 other characters you can recruit, equip and level as "mercenaries". You start out with a few mercenaries and get more as you raise your level.
Level progression is as grindy as is expected of most MMORPGs these days but it doesn't feel too grindy because the battle system is fun. You don't start out with a tutorial like other games though, the tutorial is tied in with the quests and the main "story" so you have to level up to learn things, which gives an advantage to experienced players over beginners. Beginners will then look to the forum but the guides on the forum are mostly kept vague on purpose to avoid things turning too cookie cutter in PvP.
So the only way to really learn the game is to join a guild. The guild system is nice and strategically menu-based as is the economy, ran by the action system most should be familiar with by now. I personally enjoy a good auction system and this game has a really good economy. Unfortunately not many people are too good at selling things, or there are some mechanics involved in the game that are not fine tuned correctly, because most people want to sell their goods as quickly as possible and as more goods stock up in the auctions, the prices drop immensely at random frequencies over the course of an hour, so most times you have to sell lower than most other people would go otherwise you'll be there fixing your price over and over again because nobody is going to buy your goods at that price when Joe Shmoe is selling more product at a lesser price than you are. Some people do try to find and hold a standard to the rate of currency but it depends on the market of the product in question, and as you level up then the higher level products get harder to buy and more expensive, leading you to learn crafting.
The crafting system is just you going out and fighting really. It's all just hack-n-slash anyway, strategic or not. You get the materials from monsters or by purchasing them, then you start crafting and you receive crafting points based on however many monsters you need to kill to fill your order. There is auto crafting and guild crafting but it's much slower than killing things, which is what this game is all about.
The grinding and building up of things is fun, I like earning money because I like spending money, which seems to be the other thing this game is all about. Unfortunately all that vagueness in the forum guides I talked about before doesn't do much to stop people from using the same builds and formations, because a lot of people use the same things, and the ultimate goal of every player is to get to level 100 so you can start over and create a new character with a chainsaw, which is the strongest hero character in the game by leaps and bounds, though this doesn't really stop anyone else from using the same formations and strategies, which forces you to either adapt, giving up your expression and personal style, or not do much PvP at all.
It's fun at first but after a while it just seems like I am fighting the same thing over and over again while grinding monsters in between.
The game itself is free to download and play, there is the item mall and things don't seem unbalanced in that regard, though every game has critics and people have their opinions as is expected of this genre because ultimately they want to make money.
Most people stay here for the friends they make until they move on to other games. I'm not sure what that says about the state of MMORPGs exactly but personally I don't think it's looking too good. A lot of the original players of this game have gone on to other games though, and some have gone as far as to give their things away and close their account having successfully found their "perfect" MMORPG elsewhere, but this game serves as the void that you keep coming back to until you go somewhere else.
I suppose that is something, at least.
One thing of note is that in the beginning you find a lot of gold farmers spamming trying to sell you gold for money, but once you get higher levels you don't really hear them anymore, and blocking people is really easy because the interface is really easy to navigate.
I give this a careful 8.0, because I feel that the game design is wonderful and what I find wrong with it has not much to do with the game itself, but the players. I think that is the state most MMORPGs are in today, if not arguably all of them. Until you find your perfect MMORPG, give AO a try. It's good to pass some time at least if you are burned out from everything else.