Many of you know of and have played Guild Wars 1. Gw2 takes place in the same world, with most of the same races, but other then that and the lore the game is different. So whether you loved or hated gw1 try to look at gw2 on it's own while not considering gw1.
It is a buy to play game (buy it and there are no monthly costs)
There are 5 races in the game. All of which, excluding humans, are unique races not taken from other sources.
There are 8 classes in the game.
Warrior, Guardian, Thief, Ranger, Engineer, Mesmer, Necromancer, and Elementalist.
The game is honestly changing a lot about what people are used to in mmo's.
1. Dynamic events. These are like the average mmo's quests without the need to actually pick up a quest from a npc in a town and they tend to be far more diverse then quests in other mmos. I will give an example. The first dynamic event I took place in was when I was leaving the main city as a human engineer. After coming upon a farm a little text box appeared in the top right hand corner of my screen, telling me what it was that the farmer needed me to do without even having to talk to him. There were multiple ways to complete his task, he asked that you water his plants, feed the cows, and kill giant worms in his farm, if you wanted to you could have completed the task by only feeding the cows if you want. I did a little of each to finish the task, to make things more fun a giant elite mom worm appeared and started owning up some of the other noobs, a group of 10 of us jumped on it and finished it off to get a good percentage of the task completed.
2. Changing how looting works. When you help kill something, regardless of being in a party with them or not, you get your own share of exp and loot which does not take away from the exp and loot the other person gets.
3. World vs world vs world. A pvp gameplay mode which has 3 servers duking it out on 4 rather large maps that connect to each other. Up to 200 people can be present from each server, there are pve aspects to this also. Helping get resources, building siege units, helping npc camps, etc.
4. No mana. Yup no matter what class you play there is no mana, energy, rage or whatever to use skills. Everything runs off of cool downs. (excluding thiefs that work off of initiative) You might find this weird or perhaps even bad but it makes it so there is no down time at all for mage classes.
5. The skills themselves. The skills 1-5 are set in place automatically based upon what weapon/weapons you are using. The 6 skill is always a heal skill, 7-9 are your utility skills which you can choose from a rather large selection if skills, and 10 is your ult skill (yes like league of legends) which tends to be more powerful then other skills but also tend to have longer cool downs.
6. Breaking off from the Trinity. They do not have classes set for tank, dps, or healing in this game. Each class can do all of these. This makes it so you can team up with anyone you wish to and not have to find the "proper" team comp to do questing. Every class can heal themselves or heal others if they wish to do so. Some classes will fit a role a little better then others but still any class can fill any role.
7. Dying. Dying works more like left for dead then other mmo's. When you run out of health you fall onto the ground and get a set amount of hp that slowly starts draining, while down you can use a set of skills based upon your class. If you kill a enemy while down you can revive yourself, but also anyone (regardless of class) can run up to you and help you back onto your feet once you fall down.
8. Playing with those who are higher or lower level then you. Each area has a level cap and if you are beyond that level your stats will be reduced to that of what it would be for that level, making it so you can play along with your noob friends with your main character and not be op.
9. Dying outfits. You can place up to 4 different colors on any armor set or town clothes, allowing for a great deal of character customization. There are 390 different dyes in the game.
10. Transmutation. The combining of two like armor pieces keeping the looks of one but giving it the stats of another. (not the first game to implement it but still rather rare)
11. Armor set bonus's. There have been in mmos that there are armor sets and by equipping more pieces of that set you get additional bonus's. It would become a bummer later on when you would get a better helmet but by putting it on you would break the set you have and lose that bonus. In gw2 set bonus's are gained by putting the same types of runes in all your armor pieces, this makes it so even if you replace a helmet with a new one you could just put the same rune into it and still keep the set bonus.