Despite its long years in development, many missed beta/release dates and lackluster PR, Darkfall is still the most anticipated game in the PvP community. Darkfall's list of features has attracted many people from games like Ultima Online and Shadowbane.
Open PvP - No safezones, you can attack anyone, anywhere, anytime you want. You may think this can cause a lot of griefing, and newbie killing. As far as those go - there is an alignment system which will make the players take consequences for what they are doing. If they go around killing newbies and people of the same race, they will take alignment hits and will soon become red, therefore turning even the friendly NPCs hostile towards them. Also, griefing happens a lot more in games with restricted PvP. In Darkfall, the griefers can get easily "griefed" themselves. Of course, in cities and towns there will be NPC guards who will protect anyone who isn't causing any trouble.
Full Loot - This basically means that, when you die, all the items you were wearing and carrying can be looted by your enemy and any player who passes by. This might sound pretty hardcore, but in the long run it makes the PvP and the game itself much more fun and intense. In this game, items won't make an edge like in World of Warcraft or similar games. So when you die in a PvP battle and you lose all of your items, it won't be a problem to reequip yourself, nor will you be significantly weaker than before. Of course, we haven't seen any of this in action yet.
Skill-Based Progression - There are no levels in this game. You can do whatever you want with your character. For example, you pick certain skills, and decide to become good in them accordingly. Sword fighting can be trained either by dueling, PvP-ing or fighting mobs. You just need to use the skill somehow. Of course, if you abandon a certain skill that you've trained in the past, it will slowly decay. Just like real life.
FPS Combat System - Melee attack, spells and arrows are manually aimed just like in traditional FPS games. You can dodge fireballs and even arrows if you are fast and lucky enough. It also depends on your own player (human) skills to block incoming melee and ranged attacks (that aren't strong enough to break your shield).
City Building and Conquering - There are designated areas for city building in the world, so you can't build anywhere you want. Cities can only be built by clans. We have been told that you can have cities in underwater caverns, and on isolated islands. Sounds good, doesn't it ? But alas, there's not much to say, since there hasn't been any real info in the past 2 years on this aspect of the game.
Alignment System - This is Darkfall's way of balancing random player killing. You get consequences for your action. If you do good for your race, you are closer to being a hero, while killing everyone on sight makes you more of an outlaw. The later can restrict your access to certain cities, even the ones of your own race (read: you will be attacked by the city NPC guards on sight). It was also mentioned that bounties will be generated on these outlaw players and offered as quests by NPCs, so killing outlaws will not only raise your alignment, but get you a good reward, too.
Friendly Fire - You can kill your allies if you (or them) are not being careful. This makes the player's (human's) skill even more important, as well as team cooperation, walking in formations and other things the players might come up with to avoid killing each other. Not to forget collision detection, which means that players can't "walk" through each other. Your character is an obstacle to everyone. This feature and friendly fire will make zerging (clans allying together to employ the strength of numbers) harder.
Dynamic Mob Spawns - Some creatures inhabit an area, and when players start killing a lot of them, they start "migrating" to another area, where they can survive and breed again.
There are other goodies such as crafting, player driven economy, mounted combat and naval combat. All of them making the game even more appealing to PvP players. It is true that most of the game will revolve around clans, but this doesn't mean that solo players won't be able to enjoy it. They can always do quests, hunt monsters and ingredients for crafting, crafting themselves and selling items to other players, or be the lone bounty hunter or outlaw. If you find all of the things you've read above appealing, visiting the official website is recommended for more indepth info.
Now you might say "That's great, but how do I know its all working well, and that the game is actually fun". Well, only beta and the actual release of the game will tell. I hope they both come soon.