Mixed feelings, we live in Oxfordshire, which is doing a Wales and I think the main problem is the speed limit needs to be applied selctively.
In our village, for example, no one is arguing about the residential areas going down to 20 miles an hour, but we have a major road going through the village, most of it between fields or our huge open green. Where it goes through the green there is a deep ditch either side. There has not been an accidents there in the nearly 30 years we have lived here. There is no reason why the mile or so of road going through open land should be reduced to 20mph.
In other villages, there are roads that just skirt the edge of villages, sometimes with no houses on them at all but because there is a village nameplate in two places, you need to slow down to 20 miles an hour.
As I said I am not opposed to the 20 mph speed limit in principle, I am all for it in residential roads, but I think where roads are in village boundaries but do not go through residential areas, they should be exempted.