Read that dps class breakdown a few pages back for Legion, but it was pretty grim. I'll probably stick with frost DK out the gate but anyone have anything good to say about any of the other dps specs? I'm leaning towards Warrior, Warlock or Rogue, but might try druid or monk.
So far I've really enjoyed Fury War, Marks Hunter, Arcane Mage, Affliction Lock, Boomkin, and the Demon Hunter's dps spec (I'm never gonna get their real names straight). Frost DK is actually one of the blander specs right now. It's just the exact same thing as live but with fewer buttons, and Killing Machine only affects Obliterate. Oh and Remorseless Winter is now baseline for Frost only as an aoe, damage over time replacement of Death and Decay, so that's neat I guess.
Fury has a lot of the same abilities as on live, but reworked to make the rotation flow feel pretty fun. Bloodthirst is your standard core ability; crits with it trigger Enrage. Furious Slash replaces Wild Strike as the 'I got nothing else' filler, except it costs no rage so you actually want to use it, AND it buffs Bloodthirst's crit chance by 15%, stacking until your next BT crit. Enrage is much stronger than on live; with mastery just from starter gear + artifacts it's at 60% increased damage, plus 100% increased attack speed as a baseline bonus. Raging Blow is freely usable in Enrage instead of having charges, and builds rage instead of costing it. All of this is building up to your rage spender, Rampage, which costs 85 rage, does big damage in a 5-hit combo, and triggers Enrage so you don't have to save it til you crit with BT. Overall, you spend more time Enraged, which is stronger, and you're constantly managing your rage bar, which feels meaningful for the first time in a while.
Marksman's rotation is based on proccing Hunter's Mark on your targets, which enables a single use of Marked Shot, a high damage shot that hits all marked targets and debuffs them, increasing some of your other shots' damage on them. It's pretty satisfying applying a mark on whole groups at once with Multi-shot, then causing massive destruction with a single Marked Shot. The animation fires one projectile at a time, even if you're hitting several targets at once; it just fires them very quickly. I think they were going for a 'mark & execute' style shot, like you'd see in games like Red Dead Redemption. You also get increased range based on mastery, which feels broken outdoors but pretty frustrating inside. Between the range, high burst damage, mobility (Disengage is the same, Aspect of the Cheetah is now a 12s sprint on a 3 min cooldown, no longer dazes you), anti-mobility on the mobs (Concussive shot is the same, Scatter Shot is back with an added knockback and called Bursting Shot, unfortunately no traps but some CC options as talents), and survivability (Deterrence was renamed Aspect of the Turtle for whatever reason but is pretty much the same, there's a new baseline heal for 50% hp that refreshes quicker when you kill mobs, about 3-4 kills will completely refresh it), it really feels unnecessary to have a pet. It's a shame they put Lone Wolf back as an optional talent instead of baseline.
Arcane Mage is probably not that different from on live, but I haven't played one in a while so couldn't say. What I can say is they are pretty fun in Legion while their playstyle in the past has usually annoyed me. Arcane charges are now a resource with their own bar on your character portrait; besides being easier to track without using an addon, this means they have no expiration date and you don't have to worry about refreshing their duration. They will decay out of combat though. The damage increase also scales with mastery; starter gear and artifact put me at about 79% as opposed to the static 50% on live. Evocation no longer consumes charges and just acts at the power of 4 charges as baseline now. This means you can pop Evo to extend your burn phase even longer, instead of ending it. Arcane Power is stronger but works the same (30% dmg, -30% spell cost, compared to 20% dmg, -10% cost on live). I think the best change to the spec is the mastery: besides the aforementioned arcane charge scaling, it also increases your max mana pool and passive mana regen. letting you use your burn phase longer and more often. Better yet, it doesn't have that FUCKING RETARDED mechanic of doing less damage the more mana you spend. In Legion, you get to spend shittons of mana and feel good about it, and it all comes back pretty quick.
I'm getting sleepy with all this typing so I'll keep the rest short.
Affliction rotation is actually pretty crappy. Talents can change it a LOT, maybe I just haven't found the right combination. Still, the damage is good, healing from Drain Life/Soul is pretty powerful, and the Seed of Corruption talent is absolutely fantastic, makes it worth playing affliction just for that.
Boomkin is vastly improved simply by virtue of them removing the Balance Cycle mechanic. Same spells otherwise. Moonfire, Sunfire, Wrath (renamed Solar Wrath), and Starfire (renamed Lunar Strike) all fill a bar called Astral Power, Starfall and Starsurge spend it. Moonfire and Solar Wrath are single target, Sunfire and Lunar Strike have aoe splash damage. Starsurge buffs both Solar Wrath and Lunar Strike, 1 charge for each, so you're encouraged to alternate casts once in a while and not just spam one thing based on the number of targets.
The best part about Havok Demon Hunters is their mobility. Double jump and glide are tied to spacebar. Double jump is completely client side so the responsiveness feels great; glide is server so it may lag a bit. Havok mastery increases run speed, a little over 20% with starter gear + artifacts. They also have a small quick dash and disengage-like backflip, both can be done midair. The rotation itself is extremely simple, but I don't have access to most of the talents yet.
I intended to try out every single spec during the beta, but it turns out that's kind of exhausting. Not to mention you have to repeat the introduction scenario on every single character, and even the first time it was kinda boring and a pain in the ass. About 20 times through it at this point and I usually just AFK til it's over. If I find any other specs that feel good, I'll mention it.
I'd say overall it's 50/50 whether any particular spec is changing for the better or for the worse, the worst cases being ones that are just more boring versions of what they are now. If you have 1 or 2 main characters you are deadset on sticking with in Legion you may be disappointed, you may not. But if you're willing to switch it up and play something new, there are plenty of really fun specs.