For me, the short answer is zero at the moment.
I don't like to disillusion those players who like to field them, but Furies of Chaos are worse than many (probably all) other choices in the daemons codex. For the same price as (e.g.) a Flesh Hound of Khorne, we get one less WS point, one less I point, and jump infantry instead of being beasts. Furies used to be cool in the 3rd edition chaos space marine codex. But here in the chaos daemons codex: don't play them unless you want to be fluffy. And since building a non-aligned chaos daemons army is near impossible, I don't think we'll be seeing Furies of Chaos on the table top in high end competitions.
So, my question is does anyone have experience using them, and like them? I certainly used to, but I just can't bring myself to field them recently. I strongly prefer to invest points in screamers (which are also fast, slightly more durable and pose significant problems to tanks!).