This is near where I live and it is indeed safe, mainly because everyone drives incredibly slowly and cautiously since the experience is scary as hell.
Apparently there are fewer accidents on the roads when the traffic lights aren’t working. The reason is exactly that - everyone is terrified and drives really slowly to make up for it.
Of course it's a real spaghetti intersection where you need to potentially navigate dozens of 2D roundabouts to get to any given direction. Which coincidentally also is true for the 2D road network where I live.
Bonus question: if you can, what happens if you drive a DeLorean at 88 miles/hour on it?
Every driver in the UK is used to sequences of two or three roundabouts, they are part of the driving test. As long as you are not bamboozled by the pseudo roundabout in the middle, you just navigate it based on principles you already know.
As other comments have noted, when drivers are less clear on the rules they tend to drive more slowly and cautiously - I think that makes double roundabouts "work out" most of the time.
Holders of foreign driving licences should probably be required to do a course, including these at least, before being allowed to use their licence here.
We could accomplish the same with other forms of creative driver-hostile road construction and deliberately unproductive signage.