After considerable time and hassle downloading, patching, downloading and installing addons, etc., 4.0.1 has finally arrived! I got some hands on time with the DK tonite; I tanked a couple heroics and ran a VoA25 so I can get a handle on the new mechanics.
My unbuffed HP went up about 6k, from 47k to 53k. Things that factored into this include Plate Specialization (+5% Sta for wearing all Plate Armor; this would be 5% Str if I was Frost or Unholy spec), stats and a gem socket on Sigil of the Bone Gryphon, etc. We've gained a few new CDs as I mentioned previously: DRW as a defensive CD and Bone Shield, as well as a refresh on Rune Tap from WotN. Our mastery is nice; I reforged away some excess hit and the crit on my weapon and got up to 10 mastery rating, bringing the absorb on my DS up to 64% (can't tell how useful the absorbs are since Skada doesn't appear to track them well yet).
I had mentioned previously that QA and other auction addons were broken by this patch; the good news is that a nice guy named Supa94 has restarted QA as Auction Profit Master. I'll talk more about that tomorrow, but suffice to say it's an entirely sufficient replacement for the moment.
Other nice things include 310% flying on all mounts for only 5k gold, cool new UI elements for Character, Spellbook, Mounts/Companions, Talents, Glyphs, etc., an influx of players back to the game for the patch, and all kinds of stuff I'm probably forgetting or haven't noticed yet.
The biggest negative I noticed while playing that I missed in previous write-ups is the change to Morbidity: previously it reduced the cooldown of D&D from 30s to 15s. Now, it increases damage done by 30%, but without the short cooldown AoE tanking heroics is a nightmare. I was losing threat left and right because, even specced, BB doesn't do it. We've got a glyph for longer duration but I really hope we get something that lowers the cooldown so it's available every trash pull in heroics.
Crimson Scourge and Scarlet Fever don't seem generally useful; I specced into them but found difficulty fitting BB into the rotation. On bosses it seemed a waste of a blood rune that didn't do enough threat, while on AoE pulls it was difficult getting diseases up, Pest, then finally getting to BB while still hoping to have a) aggro or b) mobs still alive. I'm probably going to drop them for BCB and/or Scent of Blood. The change to RS allowing it to be used while in Blood Pres w/o requiring dodge/parry isn't live yet, so I can't tell how much RP I'll need.
Our rotation (as intended) feels a lot more random now, due to Blood Rites (the old Death Rune talent that I never bothered with while tanking, but which we now get for free) and Runic Empowerment. Once the RS change hits, RE will probably feel a bit better since we'll be able to RS more predictably and thus get more procs.
Trade chat spam is dead; you can now only send two messages in a ~30s period. Many addons are nonfunctional or crippled due to lack of updates. Stability has been surprisingly good, however; no world server crashes, instance caps or instance crashes that I've seen. There's a new raid UI that I guess is cool if you're a healer, but I'm not so I turned it off immediately; unfortunately I can't see my party while in a raid anymore which means I can't watch the other tank for HP, buffs/debuffs, etc.
All in all a decent patch that will take some getting used to. I still need to spend my DPS talents and try frost out, and maybe give unholy a whirl too. Then there's my other 6 80s...