Well, the beta servers appear to be down for the day (hopefully for a new build, the current one has been giving both my computer and the server a lot of problems), so I suppose that means it's time for a beta update, starring Cheerydeth!
How much content should we need to level through?
My perception of the level 73-75 range may be skewed by the changing beta Exp curve. When last I updated Cheery's exploits, Blizzard had just ramped up the exp gain dramatically to see how that would work. The answer was not so well, so they ramped it back down a notch. I would easily be level 76 by now, perhaps even approaching level 77, had exp been at its "current" (perhaps soon to be changed again) level.
I wound up completing many of the solo quests remaining in the Dragonblight, both in the neighborhood of the re-located citadel of Naxxramus, and Wyrmrest temple (home to the dragon aspects). After that, I did basically the entire zone of the Grizzly Hills (which left me halfway from 75 to 76 as I entered Zul'Drak). I did abandon some of the later Dragonblight quests (since I outleveled them while doing both starting zones), along with most/all of the group and instance quests in both zones. I also didn't mess with the unfinished World PVP daily quests in the Grizzly Hills. Still, there is very little left in Northrend for under-75 characters that I have not done.
I suppose the good news is that you will get to see all of the cool content on your first pass through Northrend. The bad news is that there will be very little room to branch out into when leveling alts. Worse, Zul'Drak appears to be entirely neutral faction quest-givers, which means that you won't get to see different content if you level both an Alliance and a Horde character. In fairness, I don't typically skip entire major quest hubs in TBC content either (though Cherry never set foot in Nagrand, the Netherstorm, or Shadowmoon Valley, except to buy her flying mount training), but it's nice to have the option to blow off quests that have mediocre rewards or are otherwise a pain in the tail.
Quest variety is good
This is not what it looks like, I can totally explain.... no, no I can't.
If you're going to have to repeat all the quests on every character, at least the quests are good. I'm constantly discovering new things I didn't know were added to the game. In one example, there are a pair of warring tribes of Furbolgs in the vicinity of one quest location, and you can temporarily keep one of them off your back by killing the other tribe. In another, you can now individually target mobs and their mounts (see the unfortunate-looking screenshot). There's also a village that goes from friendly to hostile with you as you complete a questline, and some misc vehicles and guest appearences by lore characters.
It's also worth noting (if you don't get this from the screenshots) that there is actually a lot of varying scenery in Northrend. From Tundra to forest to icy wasteland (hopefully this one won't dominate everything you see at level 80) to jungle, Blizzard has done a good job making sure you don't get bored. My personal favorite is a ruined Iron Dwarf city (below), which takes the layout of Ironforge and covers it with overgrowth and ancient technology. Really, all of the art is head and shoulders above the stuff in the old parts of Azeroth.
Death Knight Talent Updates
The most recent build finally nerfed the overpowered bloodworms, this time making them so weak as to make them relatively useless. This was good for me, though, because it encouraged me to try out Unholy and Frost.
The Frost tree has a good core AoE talent spell that hits for double damage on targets affected by Frost Fever (a DK disease that you can spread around relatively easily) and is a guaranteed crit after any autoattack crit. Froststrike, the 41 point talent, does frost damage instead of physical (bypassing armor), and is also a guaranteed crit after autoattack crits. Both remind me a lot of my frost mage; you have the potential for some HUGE damage numbers with the right procs (though there may be a few bugs in the accounting, I probably shouldn't be critting for 4.5K damage on everything in a 10 yard radius).
The Unholy tree may actually be the new Blood tree in terms of healing efficiency. Death Knights have two baseline disease debuffs that they can apply to enemies, and Unholy specs get access to two more. The amount of healing you get out of Death Strike scales with the number of diseases you've got up, and I've gotten up to a whopping 3.2K self-heal crit with all four diseases going. (This may or may not also be bugged.) It's also hard to overstate the survival bonus of having a controllable pet out. Overall, I do about the same damage as Blood or Unholy, but the pet's damage makes stuff die faster (so I take less damage), and he can off-tank adds if I get multiple mobs. Bugs in the current build are keeping Unholy DK's from detonating their ghouls or sacrificing them for health, so this tree is only going to get better. In some ways, I'm fine with that; the melee pet class angle isn't really one that WoW has explored much.
The Perils of being a Beta Tester
I wouldn't trade the time I've spent in beta for anything in the World (of Warcraft). That said, playing through all this content in beta is definitely decreasing my anticipation for the expansion's actual launch. Don't get me wrong, the solo questing is as good or better than ever, it's just that I'm already going to have done most of it by the time the expansion goes live. I'm also concerned that the experience may ruin Death Knights for me. I love Cheery dearly, but it seems like she's always benefiting from one bug or another. Somehow, I think that playing the finished product may be disappointing, because it'll be weaker than what I'm used to.
I don't really say this to make y'all feel sorry for me or anything, but perhaps this will make those of you who didn't get beta keys feel a bit better. :)