1. Simplified stats and gear

If the stats system is too complicated to you, you're in luck, because Blizzard thought it was too complicated and has changed a lot of stats and gear in the game.

    There are lots of stats that you no longer have to worry about figuring out since hit, expertise, dodge, parry, and reforging are removed.
    The number of items you can enchant and socket with gems is being reduced, which means you don't have to worry about getting gear perfectly enchanted or gemmed any longer.
    There are some new tertiary stats that can randomly appear on gear as a bonus. Some of will be useful, like lifestealing on a weapon, or sturdiness to avoid durability loss on a weapon.
    Useless gear drops will no longer happen since primary stats on many types of gear will change based on your specialization. However, Jewelry, cloaks, trinkets, and weapons -- which can all be equipped by multiple classes -- will remain role-focused.

2. Raiding made simpler
Changes in raids work will make joining raids easier in the future. In Warlords, there will be four types of raids:

    Heroic: Normal difficulty will be Heroic difficulty in Warlords, and will also scale in difficulty based on the size of your raid group.
    Normal: Flexible will be Normal in the Warlords. These are flexible-sized raids that scale in difficulty based on your group size.   
    Mythic: The only fixed sized raid, requiring a set group of 20 players to accomplish them. Mythic raids will be the most difficult raid.
    Raid Finder: LFR groups are not change too much, except the group sizes are now flexible. The Raid Finder will still aim to fill the group, but if a player or two drops as you go through the dungeon, the difficulty will scale down accordingly.

3. Recruit your friends
If you buy Warlords of Draenor, you'll be able to pick any character, even a brand new one you create for the purpose, to boost immediately to level 90. This means no matter where you are in the game right now, you would jump into new Draenor content and play with your friends as long as you buy the expansion.

4. An adventure guide to help you
Though Blizzard didn't give many details here, they mentioned Warlords will have an adventure guide to help players progress. It will help you find where to go to train your professions or improve your gear. It also has an AI that will learn from your behavior and suggest things that mesh with how you like to play.

5. Your inventory will be easier to manage
Anyone who's been playing for long knows that juggling your inventory items can be a big problem as you collect things. But in Warlords of Draenor, storing stuff will be easier than ever.

6. WoW's new social philosophy
In the systems panel at BlizzCon, Ghostcrawler talked about the "social philosophy" in Warlords of Draenor. Blizzard wants you to be able to play with your friends,  so you'll get a valor bonus by queuing up with friends rather than just joining a random group, encouraging you to play with your friends.
 
7. quest system Updated
Although quest system in WOW is easy enough for most players on www.live4mmo.com, Warlords of Draenor still "refine" the quest system.

    Quests will be able to award bonus rare or even epic items.
    The quest interface will become even more user-friendly, making it easier to know where to go and what to do.
    Major storylines will be highlighted in the quest tracker, so you don't miss them -- and they'll be marked on your map, too, so it's easy to find them.