The only DWers that won't love it with all their being is a shaman, who's main damage is from yellow attacks and is special-capped stock. :P
And yeah, the hit rating is just awesome for a tank. I know in my regular tanking gear on my warrior, I sit at around 23 expertise and ~20 hit rating. That 3% from imp. FF gives me an extra 48 hit rating (I think), so it adds a pretty decent chunk to my TPS.
Like I said, though, DWers will basically never be hit capped, so it is always a good thing for them. And like Rarebeast said, the hunters, druuids, ret pallies and 2h warriors can shift their gear to drop some hit rating and have more AP/crit/whatever, increasing their DPS. It's a damn good talent.