Diverging Diamond Interchange comes to Washington State (2016) [video]
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It seems to me it's trading a separate phase for the left turns, in favor of "everybody has to make a left turn", and those wanting to proceed straight also have to cross traffic again. So I'd imagine this probably does work better for people who wanted to turn left, but worse for people that wanted to go straight.
And during low traffic periods, anyone wanting to go straight will have to stop at two lights rather than just having the lights default to green unless a car shows up at one of the sides.
Maybe they're better, maybe they're worse, but more likely it depends on a lot more things than this video lets on.
making two 36' crossings is a lot safer than a single 72' crossing. narrowing the crossing width is a good thing in intersection design, even if it takes a bit longer. It's a fairly long walk for for a pedestrian to make, waiting for an extra light isn't going to make a significant change to the crossing length for a pedestrian.