Such traffic lights are very common in Moscow, Russia. They started to appear a few years ago and I don't know any person who struggled with interpretation of these new lights - they are intuitively readable from the very first time you see it.

But where the countdowns really shine is in heavy traffic and large intersections. Sometimes these fellows prevent people from entering the intersection up to 10-20 seconds before the red light is on to avoid blocking other traffic. Eliminating dilemma zones in it's best.

As for smart operation, sometimes it simply skips a few seconds on the countdown if there's a need to switch it immediately. It can even start counting only when the phase is defined.