That awkward moment where you're not sure if you should join the guild or not because you already have 49 toons and rolling one on Thunderhorn would max you out on characters.
With how easy it is to have alts now, they really should increase that cap...
Been in Draenor for a while and it's... well... the leveling experience is the best I've seen but I can't say the same for the endgame content right now. They screwed up pretty big with endgame. The atmosphere is absolutely amazing while leveling; Blizzard did a superb job at making this world feel truly alien. Previously I've had issues with every new zone feeling like a rehash of an old one and this time, its only Frostfire that feels like a rehash. Just don't look up in SMV or you may end up staring at the skybox forever like I did. I pity anyone who doesn't have a good enough GPU to run on ultra or at least high. Everything looks amazing, and WoD added the minor feature of ground clutter crash moving when you run through it.
The story is a bit linear, but great nonetheless. Yrel is a breath of fresh air considering most of Blizzard's female characters have either been unstable, only exist as a romantic sub plot, or basically just had their lore built up only to be shoved off to the side. They do go full GoT and kill off a bunch of characters though (even though some are AU characters so not technically dead). It's great to finally be getting some Draenei lore, and possibly an excuse for Draaenei rogues and druids sometime in the future (Rangari)? Velen really needed to do something other than sit at the back door of the Exodar presenting his own back door to any Horde who so desired.
Garrisons are a great time killer with some awesome benefits, such as the Enchanter's Study which allows you to use Illusion Scrolls on your weapons to give them the look of any enchant without having to use something inferior and outdated (sorry, Hunters can't take advantage of this). It's nice to have a time killer that isn't dailies, dailies, and more dailies.
Gearing has changed for the worse unfortunately. On the upside, quest rewards have a chance to be upgraded to rare or even epic upon quest completion. Its also nice to only have to caryy one set of gear for two different specs. The downsides are crafted gear now takes ridiculously long to make and the stats roll upon creation much like Timeless Isle tokens, meaning if you're a class that relies heavily on your secondaries like a Fire Mage or Fury Warrior, be prepared to clench your anus in fear that you might get a piece with no crit and both of your worst stats. Dungeon loot works the same way, and for whatever reason when Blizzard carried the personal loot system from LFR to 5-mans they felt it necessary to bloat loot tables to 40-70 items meaning if you're trying to fill a specific slot you have better chances running for president with a shoe on your head.
A few tips on leveling through Draenor:
Do Bonus Objectives (the brown dots with gold crossed swords on your map) they give a lot of XP
Grab guild battle standards and use them whenever you can, especially during the above
Nagrand has a breadcrumb quest in the SE which gives you a one hour 5% xp buff, there are treasures in Spires which can be looted for an XP buff as well
There's far more treasures and rares than there were in Pandaria and getting the addons Handynotes and its Draenortreasures plugin are recommended, but keep in mind rares dont give as much xp as they did in Pandaria, and treasures only give about half a bar.
There's gold elites in Gorgrond for the Gorgrond Monster Hunter achieve. These drop a quest, so they're worth killing. Just keep in mind there are elites out here who aren't part of the achieve, are raid bosses, and will push your face in, so check how much health they have first.
Dungeons give didly shit for xp, likely because Blizz wants people out in the world, so its not worth it to level through them
Once you get past SMV/FFR you'll be given the option to choose which outpost you want for each zone. Changing your outpost will set you back 10k gold, so choose wisely. The Gorgrond and Talador outposts reward different followers.
When leveling, the best garrison setup once you get to rank 2 is: Lumber Mill, Bunker/War Mill (replace Barracks by dragging a building over it), Enchanter's Study, [profession]. You'll get one profession building automatically, the Enchanters study will allow you to DE almost anything which will be useful later on and depending on your server the DE mats might sell for more than what the items vendor for. The Bunker/War Mill increases your chances of getting rare or epic upgrades from quests, and it feels like its been working for gear looted from rares and treasures too. The Mill will help you with resource production, as resources don't flow in like Lesser Charms and you'll need 3k to upgrade to a rank 3 garrison and 900 to upgrade your large buildings.
At 90, garrison setup is up to you. Bunker/War Mill is now for xmog, Barracks can be brought back for follower benefits, Inn's daily quests give some nice toys and you can get a shiny new follower every week, I'd suggest keeping the Lumber Mill or using one of your small buildings for Salvage Yard because of the resource gain. Those are really the only non-small buildings I have experience with but WoWhead is swimming in Garrison guides.