Below my disc bike which has been on the road since October. I think it must have cost about 20% of the gorgeous bikes pictured above, being based as it is on a Chinese AC024 CX frame and some components carried forward from a previous bike. Bit of a budget weenie project. It was intended as an all-weather bike and as I've just come back from 43km in 5C and light rain I can say it's fulfilling that purpose admirably.
The brakes are excellent. As someone else pointed out, modulation is a strong point. So, surprisingly, is silence. Rim brakes in winter round here grate horribly against the rim because of road grit. That hasn't been an issue with discs. They are not immune to water, it slows the response but they get there. In the dry they have a lot of power. They're 160mm front and rear. I think there is certainly an argument for dropping to 140mm, at least for the rear.
I'm now pretty sure discs will take over for road within the next 5 years. The delay won't be the brake technology, it'll be the industry tooling up for mass production of disc groupsets, frames, hubs, rims and so on. It's a huge opportunity for the industry, no question, but the bikes will be good.
As for the pro ranks, Wiggins might have appreciated discs on those wet Giro descents last year. I don't buy that they'll slow anyone down in bunch racing.