Another Mist of Pandaria patch would delay Warlords of Draenor, so Patch 5.5 isn't going to happen. The entire team is working on the next expansion right now, so any more Mists of Pandaria content would slow down development. But as of now the release date is unknown.

The level cap has been raised to 100.

Levelling doesn't feel as exciting as it used to, so Blizzard will try to address that.
From level 91 to 100 you will get upgrades to your core spells. Some will be slight class changes, some will be passive bonuses, similar to old spell ranks. Some of the boosts will definitely be easy to feel.

Quest chains that are important and have important lore and story will be indicated with an icon. There will be more optional content and less quest hubs that have to be unlocked by another chain first. The dynamic events from Timeless Isle will appear in the world when you are leveling and Level 100. Right now they are mostly soloable rare spawns, but the WoD events will be more complex and not soloable. Treasures will be hidden down paths that quests don't send you down and found frequently. They also will have a small amount of story to go with them. Quests will have a chance to give you rare or epic rewards. The quest UI has been updated to combine the map and quest log and help guide the quest experience better. The map will show you where you left off on the important storyline quests. The world will be more dynamic and less predictable.

[ Register or Signin to view external links. ]
[ Register or Signin to view external links. ]
[ Register or Signin to view external links. ]

There will be a legendary questline again. The questline will be a little bit more custom to your class to help with the lack of class quests. Class quests are very resource intensive, so at most we might see one or two.
Levelling will be a fun and fast paced romp through the zones. The team is backing off the idea that levelling should be a long grind.

The new Normal will be as difficult as Flex is today. The new Heroic will be as difficult as Normal is today. The new Mythic will be as difficult was Heroic is today.
Each raid difficulty has its own lockout. Raid Finder will be the only kind of raid you queue for.
Loot will scale based on the number of players, giving you a higher chance for another piece of loot the more players you have. This ensures there are no optimal breakpoints that would limit raid size to get more loot.

When you build your Garrison, you will get a few starting buildings. The Town Hall is your main point of interaction and is automatically placed. All profession buildings are in the Small Buildings category. They will allow you to use an engineer follower to run missions to get engineering recipes and items. The pet stable will have a trainer you can fight. Large buildings are something you would expect to see in a WC3 base. Each building has a bonus. For example, the barracks will let you have more followers. Buildings start out small and are upgraded over time. Some upgrades can be purchased, but some are blueprints that you find in the world. They can be faction rewards, quest rewards, random world drops, or found in other ways. Specializations allow you to customize a max level building. They can be changed once each day and may have a cost. You pick from one of three specializations. Some buildings will allow you to assign followers to them. If you find a miner follower, he can work while you are offline collecting ore. Managing your followers will be an important part of garrisons. Fill plots to upgrade your tier. Plots come in multiple sizes. Followers can be sent on Quests, Scenarios, Dungeons, or Raids. Raids may take party of a week and many followers. You put the followers into a party and send them on missions. You get a bonus if you match traits on your followers to the missions. When you send your follower somewhere in your Garrison, you will see the follower there.

[ Register or Signin to view external links. ]

Alliance: Karabor, Shadowmoon Valley.
Horde: Bladespire Fortress, Frostfire Ridge.

Blizzard be introducing six new dungeons and bringing back a classic: Upper Blackrock Spire.
This dungeon will play a prominent role in the Warlords of Draenor storyline, and Blizzard are excited for people to experience this beloved old dungeon in an entirely new context. Here are the names of all six dungeons: Bloodmaul Slag Mines, Blackrock Depot, Auchindoun, Arakkoa Spires, Shadowmoon Burial Grounds, Iron Barracks and Returning - Upper Blackrock Spire.

Blackrock Foundry, Highmaul and world bosses.

[ Register or Signin to view external links. ]

For a full detailed and official description on the new UI coming up, visit [ Register or Signin to view external links. ] link.

Sorry for linking you away again but there is far too much to write put on here so follow [ Register or Signin to view external links. ] link for a in depth description of new features for PvP.

The level 100 talents have been released, click the link below and you will be able to navigate through them.
Bare in mind that these have a chance of changing before the game is launched.
[ Register or Signin to view external links. ] .

Sound shouldn't be annoying, which is part of reasoning for the new Hunter weapon sounds. The last time there has been so much diversity in the sound required for the expansion was likely Vanilla. There is a lot diversity in the races and zones in Warlords.

The video above shows you how recruit a friend has been updated. With the new system you can recruit players who have World of Warcraft accounts that are less than 30 days old. Simply use the standard Recruit A Friend process. When your friend receives the email, clicking the link will bind your accounts for recruit a friend rewards and benefits.

Blizzard will be giving you the chance to create a character which will instantly be level 90 and will have some decent gear equipped when Warlords of Draenor launches. This only applies to people who have owned the previous expansions before Warlords of Draenor.
There will be a sort of starting zone for these instant 90s just like the Death Knights had at level 55.

Gear will be receiving a squish and a few stats will be removed from the game.