Games Workshop are doing a big Chaos release for WH and 40K soon, including a revamp of the daemons. Some of them could probably do with it, but others I'm not too sure about.
I started gaming with the 'classic' daemonettes - big lobster claws, normally bald, pallid skin, and with very strange feet. The only decent photo I can find for those who never saw them is part way down this page as "Dämonette - Dämon von Slaneesh"
Games Workshop then updated the daemonettes. Gone were the huge red claws, in were smaller, sleeker, spike-like claws that were often dark. They also became a lot more obviously female for supposedly androgynous daemons. The hair was a bit strange, possibly a bit like tentacles, but overall not a bad change.
The latest Daemonettes I'm not so sure about. On the plus side then they at least they are more androgynous. On the down side their faces look a lot more like Joss Whedon's vampires from Buffy the Vampire Slayer. The purple paint scheme, while in-keeping, doesn't seem right. The huge hair on some of them is decidedly odd as well, especially when they paint it pink!
It may be nostalgia, but I think I like the older Daemonettes (4th/5th Edition) over the 6th and 7th Edition ones. If I had to rank them then at the moment the newest incarnation gets bonus points for being a multi-part kit (and so hopefully cheaper to build for an army) but I think they rank bottom of the three.