|This book better not suck.|
One part of me is excited that Dark Eldar will get a new book, the other part is apprehensive because they're a tricky army to get right. They exemplify what it means to be a glass-cannon army, and that can be really difficult to design in an atmosphere like Warhammer 40K. I really hope that the design team gets it right this time around.
As for things I would like to see, it has to be either damage increased across the army, or the army gets cheaper. It's really that simple: More points buys you more units, which in turn buys you more guns. Or better quality guns buys you more hurt. I would be fine with any of these. I'm not going to talk any more on this matter because I don't want to set myself up for disappointment. The latest string of 40K codexes have been pretty stale as the books seem to be streamlined at its core. A lot of what was the previous Space Wolves and Grey Knights have been gutted for something much more simple.
I can only fear the worst for Dark Eldar, so I'm not going to make another comment until I get the book in my hands. For better or for worse, I will be playing a few games with my favorite army of all time. I pray that the Voidraven will be dropping large template bombs, because a small blast template as the "triumph of Dark Eldar weapons tehcnology" is a god damn joke.