Roundabouts should have only 1 direction you need to look at to cross. You don't have to watch 3-4 different directions like at a 4way stop.

That said, if there's a huge bias towards cars coming from one direction (or out one direction), that can be very difficult to cross. And it has impacts on the roundabout's throughput too, and means that a roundabout might not be the most ideal. Similarly to how a roundabout that gets backedup into can fail catastrophically (you have to make sure there's negative pressure!)