it seems so.... useless. We don't get a stealth speed bonus anymore now it "provides immunity to movement speed impairs" or something along those lines. How is this supposed to be useful?
....The set is broken guys. Don't judge the change till it's functional.
And for the record, the set says negates stealth movement speed reduction. What this means is simple:
When stealthing your movement speed is lowered. With this set, your movement speed wont be lowered. I'd imagine it'll end up being just as effective. (If the set were actually working, we'd be able to see the change, but it's not working, and it's in the Known Issues thread. It will be fixed next patch.)