I dunno. I feel a bit uncomfortable complaining because it's just a beta and the real thing will be light years different. Also the fact that my characters are facing extinction relatively soon has to play some part into it. I'm just gonna dive into some things I dislike about the game.
There's one reoccuring thing that I absolutely loathe. There's almost no customization in this game. Almost no variety as far as features of character go. The majority of skills are available to every single member of any given class, and the ones that aren't aren't desireable at all. Piss poor talent lines with negligible effects. An absolutely crappy item system that has currently nerfed any item that isn't +stats into uselessness. Not to mention that each class is so reliant on a certain stat there's no reason at all to boost a different one. Either that or they are so reliant on all stats they go crazy (druids) or stats do so little to improve the class items are boring (mage, i'd imagine warlock). I also don't like the holy trinity gameplay, but that's more to do with how effective some classes are.
At the moment there's very little incentive to level up. Congrats, you get to use a different shoulderpad that has an additional 2 spirit. Congrats you can get the 7th rank of a spell you've had since level one. Congrats you get a talent point you can invest in one of three skill lines that do almost nothing to affect the way you play. The only real reason to level up is to experience new content. Which is nice, but takes away joy of gaining a level and focuses it on getting to a level. Not to mention alot of content has yet to be added or needs more polish.
Class/Race quests. One of the "selling points" of having fast leveling is that you can make multiple characters. Aside from the obvious horde vs alliance, very little changes from character to character as far as experiencing the game goes. You do the same exact quests and have access to same exact instances. There are a few class specific quests, and if they fully implement the ratings system there probably will be race specific quests.
There's also a whole bunch of class issues. Druids are by far the black sheep of WoW. They have no use for weapons and are dependent on every stat in game depending on form. Hunters and mages are far inferior dps classes compared to rogues, hunters because the ranged weapons they need haven't been added and mages because they have no way at all of sustaining dps and only approach useful burst dps against swarms using aoe.
Blizzard. Yes, I realize that alot of mmorpg companies are insanely frustrating, but that doesn't excuse Blizzard. Currently they seem to be balancing towards pvp at the expense of pve. Plus they either completely ignore their community or give such large blanket statements they effectively say nothing. A big huge thing on the beta forums a week or so ago is some blue asking for questions from each class to bring to developers. A few days later one question from each class, a complete fluffball in every single instance I checked, got answered then a week after that an explanation of the roles of each class that says absolutely nothing new. This was the entirity of meaningful blue text for that week too. I don't think their past record really speaks for them as much as their supporters claim either. I remember back when TFT got released and nightelves (a race balanced on the fact they have no meat to tank with) abused beastmaster and bear (a free unit better than any tier 3 meat in game and a str hero), their justification for not nerfing was that "Bears should be scary". However that said, the GMs in this game have been nothing but fast, responsive, and useful. It's just the interaction between forum poster and whoever the middle man is before developers that's aggrivating.
I dunno, alot of these won't really matter as far as playing retail, they just make me go batshit insane in beta. My mage has become a complete bore to play because of a combination of the content/talent/item issues, so I quit. I'm confident the content thing will be changed, although talents probably won't. The issue that will make or break whether or not I play retail is the item system. I will never be able to get excited about +stats, especially when those stats don't tie into dps at all.