Dark Eldar rules are out everywhere, and though I still haven't got my grubby little fingers on the actual book, I basically know the rules/point costs of stuff. So far, I'm nervous.
I'm not really even sure where to start, lol. I guess I'll start with the weakness I see as the most glaring: lack of anti-tank. I think that to be a contender, Dark Eldar need to be able to consistently pop AV12 (because of IG Chimera chassis spam), and that they are exceedingly inefficient at said proposition. The single lance/melta weapon that they do have is S6, which makes popping a Chimera as difficult as killing a Land Raider.
Here's what I envision happening against Imperial Guard:
-Dark Eldar most likely get first turn (if they took Vect).
-They surge forward on turn 1, and are all up in the face of the Guard player. Easily within assault range next turn.
-Ravagers fire, kill a chimera or Vendetta, shake/stun 2 others.
-Imperial Guard go, kill most of the raiders
-Dark Eldar are happy, because they can assault this turn, right?
-They don't really have any reliable way to pop lots of AV12 up close, and end up assaulting the wall of Chimeras that moved an inch each, likely stunning/shaking a couple, destroying others (remember, DE don't even have fists in their squads). Doesn't really matter.
-The guys inside the Chimeras get out, and no amount of FNP (which you likely haven't earned yet, since vehicles don't count toward STP) is going to save you from that many las guns/flamers.
-Dark Eldar have a sad face, and get stompt.
I'm having trouble seeing other possible outcomes, honestly. Other armies, the Dark Eldar can likely hold their own against, since nobody does mech as well as Guard. Still, Guard is a popular army, and if you can't win a game against well-played guard, why go to the tournament in the first place?
The other thing I'm somewhat worried about is that Dark Eldar have no real mechanism to help with reserves. If you want to reserve your army completely, it will come in piecemeal, and end up getting wtfpwned one raider at a time.
One thing I thought about was using WWP shananigans, moving a single raider full of Wracks and a Grotesque, up 12", and dropping the Portal. The portal being 24" on (at least, more like 26"), you can have your foot-slogging horde come in and beat the pants off of their target. I just don't think it's reliable. Blood Angels, Guard, even Nids have a way to get better reserve rolls. If DE don't have any sort of help this way, it might really go hard on them. Demons get a guaranteed half of their army on the table to start the game, and they still lose games because of inconsistency with reserve rolls. Dark Eldar are even more fragile- no way they can come in piecemeal and still take the day.
I'm not all doom and gloom however- lots of cool stuff possible. If there turns out to be a way to reliably open AV12 for Dark Elves, they'll have no problem at all eating the contents. I'm really not worried about combat-y armies, since any points that are shoved into combat ability means more survivability of raiders. If raiders survive, Dark Eldar are fast enough to win the game through sheer speed and options.
Anyways, those are the things that make me nervous. I hope they end up working out, I've been excited about this army for a long, long time. These are just the problems I'm currently thinking about.
Do you have any concerns about the new Codex being competitive? Or maybe you already think they're broken :P You should let me know!