Ok NDA is lifted so I can post this. I've had a chance to look around WOTLK beta and some thoughts so far:
* Visually it is very polished, as you'd expect. The problem is the new zones aren't homogenous, like in TBC where all of Zangarmarsh has same theme. So the zones feel like a theme park, as if one bunch of devs developed their quest hub independant of another and they all just got sewn together like a patchwork quilt. Taken in isolation some of these mini zones are very nice indeed, but there's no immersion factor when you can see a totally different sub zone nearby. I found myself often thinking "but why is a camp of A parked right next to camp B with no interaction between them". I don't think this will change at release, its a design decision.
* Quests are just more of the same that we've already seen in TBC - kill, gather, escort, bomb, visit locations, you know the drill. There are a handful of quests I've seen so far that break the mould, but too few. Most are quite transparent reclones of existing quests. I know it must be hard to think up new formats, but seems to me they haven't really tried. Feels incredibly samey.
* There's some new mob types and some are great. A few have some new AI. But mostly mob is AI is the same and a large percentage are mostly just reskins of current mobs. Expect lots of variations of things you've already seen. Again, feels very samey.
* Its an enormous grind fest. I levelled from 70-71 which doesn't sound much. But it took me a week of playing several hours a session. If you maintain many alts some are going to have to fall by the wayside.
* Crafting is just a further extension of the current grind, with another tier of mats to farm. The new Inscriptions thing is going to be a grind fest and then some.
* Gear itemization from quests is as poor as ever - endless boots and gloves as quest rewards. But your level 70 epics aren't under any immediate threat, initial greens are no match. This may change but I think its a design decision not to replace hard earned epics too soon, which is no bad thing. But then if current gear is good to 75 and maybe above, you have to wonder what the point of the levelling 70-75 actually is.
* Here's the real crunch. You know that wonderful epic flyer it took you months to grind the gold for? Well you can't use it in WOTLK zones until you're level 78. Yep, you arrive in Northrend and are relegated back to ground mount. So the majority of your levelling will be with ground mount. To me this is the #1 showstopper. It just doesn't feel like a progession from level 70. We're all so used to flying around at level 70 that it feels wrong to not be able to do this in WOTLK. I can understand it would have been difficult to stop players bypassing content, but they should have found a better way ... IMO WOTLK should have been oriented around flying mounts and optimised for it. To just say "we can't be bothered to think of a way to prevent you bypassing content, so instead we're going to just artificially ban flying mounts" is just lame lame lame (especially when you watch a level 78+ fly over the content you're forced to ride through while having an epic flyer in the bank).
* Dark Knights are going to be so Zzzzzz you'll scream to see so many of them around the place. I guess this is what comes of only introducing one new class not several as most games try and do. Everyone and their aunt will be levelling a DK, though the one thing that might mitigate numbers is they have to start from level 55 so you'll be taking them through old school zones and then through the TBC grind before you even get to the WOTLK grind. Ouch.
* I've not been able to see the new PvP BG. But really, just the one BG and one new arena is hardly any committment to improving the quality of PvP gameplay. Its almost as if they are accepting that anyone that wants proper PvP should look elsewhere (i.e. WAR).
* There's no new ground breaking feature to blow everyone away with, to strive towards with excited anticipation (e.g. flying mounts in TBC). I'd go as far as to say that WOTLK is almost blatantly and unashamedly a grind fest, they don't really even attempt to hide the fact that they've raised the bar just to keep subscriptions coming in.
My prediction for WOTLK is its an expansion too far, there's just too much content to grind through now. I'm not saying there's no merit in any of it, there's probably plenty of fun to be had from it. But if you're already experiencing WoW burnout, there's nothing in WOTLK to refresh your enthusiasm. It really is more of the same, but it feels like a second helping of stodgy pudding ... can anyone really take it?