Having had a bit of a chance to peruse the "new" dark eldar, my conclusions are basically:
unimpressed. They're not without their merits, but basically a lot of cool stuff has been removed and there's the inevitable push for bigger units and more spend. It's reached the point now where they don't even seem to be trying to hide it. A prime example is Cronos and Talos (the big floaty dreadnaught sized things.) They now come in units of 1-3. or 5, if the rumours about the Covens supplement are to believed. Because what 40k players really need is units of dreadnaughts

Other units have also gotten bigger (court of archon) have also gotten bigger. To be fair, at least these increases are optional (i.e. theyre 1-3 not just 3). The aforementioned coven 'dex also bugs me, as it (along with all the others) clearly just a bunch of material that should have been included in the original book. Also, while I appreciate this was just a rumour which didnt pan out, it would have been good to see a model for Vect and his dais. The DE lack a big uber-unit (dreadknight/wraithknight/lord of battle etc) and this would have been spot on. It would also have been inspiring and cool and a (probably) kick ass model. Had this been included in the release I can't help but feel my reaction would have been "oooh, cool, shiny new dark eldar. Let's buy stuff!" Whereas, instead he was removed from the codex completely, leaving me rather flat. Don't get me wrong, I'm not lamenting the loss of Vect (which neither I nor anybody else I know of ever used) I'm more lamenting the loss of variety and potential creativity in the game.
On the plus side, I do actually like the 3 new character models we got. True, they're replacements for 3 character models that DE already had, and so add exactly zero to the range of units available, but in their defence they are nice kits with good dynamism and detail. Also, the more I look at the VoidRaven the more I like it. It's the only thing in the new releases that's actually on my "hmmmn. One day if I have money I might..." list.
Finally, I like that scourges and mandrakes are now once more viable units. They've always been cool minis, and it was a shame they were so bad rules-wise they were largely unplayable.
So, those are my thoughts. How bout yours?
@Prim: What I lost was an IC on a skyboard that made hellions troops. None of those are options in the new dex. Now I have a whole bunch of hellions and a Sathonyx that I cant use...