Focusing on the 2 dps specs, there’s overall a lot of good changes, class tree is a lot better and there’s nice additions to make frost function better with BoS in particular, while unholy has a few interesting new talents to make it revolve less around 3 minute cooldowns.
I’ve written up the biggest issues I noticed through beta in both raid and m+ testing (and just hitting dummies too) below:
Unholy
Abomination is the kind of thing that I think should be a choice node with army, rather than essentially costing us 2 talent points to get a cooldown. The fact it seems a lot stronger than army even with a bug reducing its damage by a lot, means it would be a pretty easy choice as it stands (and also because of the horsemen interaction, which I’ll get to later), but the problem is that army of the dead is just a pointless filler node - it exists just to drain a talent point so you can get to abom. In fact, it’s not even a filler node, it’s just a straight up lost talent point. Also, his slow move speed is horrible in pve and his ai is terrible.
Speaking of losing talent points, a lot of the late choices in the unholy tree feel pretty bad as 2 points. Festermight is a mandatory 2 points, so is aotd/abomb as said above, and you are realistically always taking unholy assault, so there isn’t much choice left, you pick your cooldowns and festermight and then you go into superstrain or commander of the dead, with the last point for death rot or doomed bidding. Morbidity and unholy aura stand out as especially boring filler nodes, with one basically just being a damage increase and the other turning you into some sort of totem. Decomposition is absurdly weak in all scenarios and costs 2 points too, so it either needs to be buffed a lot or moved earlier in the talent tree, probably a mix of both.
Frost
Icecap being 15 seconds cdr is very awkward. for BoS, it means you would probably delay breath 15 seconds every time because it is now short enough duration that you really need to align it with pillar, and for obliteration, although it’s a much smaller issue, the same thing applies to empower rune weapon cooldown.
Shattered frost consuming razorice feels quite bad. razorice is a debuff you apply to deal more frost damage, so every time you consume it all, you’re reducing your frost damage until you stack it back up - and then you consume it again. I don’t know if it matters much numerically, but it terms of gameplay it feels a bit bad to me, and also probably costs you a runeforge, since other builds can apply razorice through other means.
2 points are essentially lost by being stuck with frostworm’s fury and absolute zero even in ST because of riders, which hurts builds a lot, but again I’ll get to that with horsemen.
Death and decay still just feels bad for frost. For unholy and blood it doesn’t feel too bad honestly, but for frost it just feels so dependent on it for aoe.
Rider of the apocalypse
By far the biggest issue is the final node, where all four horsemen are summoned for a specific talent. Worse for frost, because you might not even take FWF at all for ST, but both specs are effectively locked into 2 talents points late in the tree because the talents that reduce the cooldown of these abilities by 90 seconds still spawn all four horsemen. I think this node needs to be tied to something else to spawn it, or nerfed by half when using raise abomination or absolute zero, because it contributes to some already strained talent trees.
Other than that the tree is quite passive, both Trollbane and Whitemane’s abilities interact with the player through scourge strike, which you’re probably pressing anyway, and Nazgrim’s is realistically not going to change anything you do - if things die while he’s up, that’s good, but you were trying to kill them anyway, not just to increase his buff. Mograine’s is the annoying one. The death and decay in itself is not overly useful, since he’s likely to spawn when you have it anyway most of the time, and as unholy you would want to press defile regardless for the damage, but he gives you 5% damage if you stand in his. That would be great if he just stood next to you, but he doesn’t, he runs to stand where pets always do, and having to chase him around on bosses with big hitboxes or where positioning matters means you can’t really make use of it, and it’s frustrating. I think Mograine should just get a different ability, and the other three are probably fine when bugs are fixed. It may be quite a passive tree, but I don’t think that’s an issue - hero talents don’t need to dramatically alter gameplay.
San’layn
After a few revisions we at least got away from the vampiric strike super spam, but there’s still some issues like the rng on extending essence of the blood queen between cooldown windows, the rng on blood beast spawn, who can spawn long after you’ve done most of your shadow damage and also just blow up after a pack dies or when a boss jumps away. I think blood beast should just spawn one at a time when you activate gift of the san’layn, and essence of the blood queen either needs to have a reliable extend mechanism, no extend mechanism at all, or just be active during gift of the san’layn.
Infliction of sorrow is also a pain point because it’s something that’s just always going to be either problematic or borderline useless. In the last iteration it was so strong that we just wanted to press vampiric strike at all costs, now it looks so weak that it hardly seems worth the amount of effort it warrants. It would probably be more fun to just rework this.
Deathbringer
The glaring issue with this one is the rng of reapplying the mark. If that procs, you get the full effect of mark and exterminate again right away, and a chance to proc it again after that. It’s like a slot machine, it’s so rng it hurts and I hope I don’t have to play it ever if it stays this way. It really does ruin the tree entirely by itself.
Aside from that, the main things I’ve noticed are that the rune cost is tough to fit in, especially now with the dramatic reduction in resource generation for frost, and it’s hard to line up with icecap specifically, which makes it feel all around awkward for the spec.
Another thing I noticed is a lot of emphasis on making abilities do shadowfrost damage, but outside of helping stack reaper’s mark a bit, dealing shadowfrost damage has no advantage in almost all situations? There’s no bonuses in or outside of the tree that benefit frost for doing shadow damage or blood for doing frost damage, the only thing it does at all is help stack reapers mark, which feels very underwhelming.
Quick side note I forgot to mention: Abomination limb feels like an extremely weird ability right now. It’s a 2 min cd which doesn’t line up at all for unholy, and while it does line up for frost, all this ability does now is some minor damage, but it has no competition in the talent tree in terms of dps so you always take it. I would have been happy to see this ability go after Shadowlands, but if we have to keep it, then you might as well just remove the damage and make it a utility talent for if we need to grip a lot of things. The visual is annoying and it’s boring to press.