No video game in the history of video games has ever accomplished the one goal every developer has set for themselves: The ability to make every single player around the world happy with the game.
As someone has been here since the Molten Core patch in Vanilla and has Beta Tested Mists of Pandaria, I can say that I am absolutely excited about this expansion. I've seen a lot of system changes from Burning Crusade to Wrath of the Lich King to Cataclysm, but I think what frustrates players is the addition of a lot of new things at once.
Each class, each expansion, received a handful of new spells and abilities while current class mechanics had changes that could be adapted to easily. Mists, with the talent and glyph system revamp kind of unloaded a LOT of new abilities or reworked mechanics on the player base all at once.
This isn't necessarily a bad thing. So things about your class changed, but for me, it's the challenge of re-learning your class.. or better put, re-exploring the way your class handles and to develop a new playstyle from it, because let's face it... pushing the same buttons over and over and using the same mechanics for each spec becomes boring. You have to switch it up to make it interesting and I think Mists does that.
For example, Im used to Frost being the PvP spec for mages so I tried it out. There were times where I forgot I had Frost Orb, Frost Bomb, Frost Jaw and a lot of the new spells. But I started to work them into a rotation and found out I had a huge level of control. I went into a 48 minute duel against a Paladin as we both never ran out of mana and couldn't kill each other. Playing with the new glyphs and testing them is fun as well as I can develop a unique playstyle that fits me versus the old cookie cutter talent specs we had before.
The system isn't perfect and no system Blizzard comes up with ever will be, but to dismiss it when the patch has been out for 24 hours and not taking the time to actually have fun with the changes is jumping the gun quite a bit.
That is how I feel leveling is for, learning your class as you advance up, learning new skills and seeing how they work. It isn't remotely fun to have to relearn your class after you level, because the point of leveling was learning your class. I feel that is part of the problem, but really my issue is the big three, lackluster talents for my main class, a cheap world event, and gylphs that break the market once again.
Really I was happy about the new mounts, monks, pandarians, and even the awesome Asian feel of the new continent. I log in with hesitation as I was following annoyed about rogues and decided to see for my self if my fear were true. It was worse, I not a fan of the over stuff spell book, I prefer the three school method, that is exponentially helpful for a caster class and knowing about the different schools of magic and the lockouts during interrupts. Not only that knowing on my Ret that holy is where I could find my healing spells was helpful than having to read through each spell to see it. It is these little things that are bothering me, you can't expect us to give us a big meal and then skip out on the condiments, silverware, and plates, it feels like the little things have gone past the beta and it is ruining the game. I have little hope for the next expansion since it is already foreshadow by our talents they will once again rework it.