For mono Slaanesh, I'd say it's perfect.
If you were willing to use other Gods, I'd suggest adding at least one unit of 6-8 plaguebearers or 5 pink horrors w/bolt, just for objective grabbing. Also, cutting back on some of the fiends and perhaps one KOS, and replacing them with DP of Tzeentch w/bolts might help balance things out.
However, as I said, if you're keeping this mono-Slaanesh, the list looks great.