I still find the nerf a bit too harsh. For pve, it changes nothing, but in pvp, it makes a whole lot of difference. A good healer always dispels it before even 1-2 seconds passed.
And let's face it, 120k crits ( mine were usually @ 100k tops on good pvp geared ) every 10 seconds or so ( 6 seconds to trigger, 4 cooldown ) inside a DF is not a big deal. Warriors, warlocks, priests, and basically every other class can pull 100k+ crits without such restrictions as frost.
Call it what you want, but the nerf was only aimed towards something easily avoidable ( exiting / avoiding DF> Dispelling / reflecting / absorbing FB )
Also, my question still stands. Will haste be more valuable now since the nerf? The damage from FB benefited solely the mages that stacked mastery > 40% for that big crit inside DF. Now, I'd rather get faster casts > dots.