I like roundabouts better than the alternative traffic lights, because most of the while traffic is moving. I was brought up with them, so they are normal to me, but as traffic volumes rise and immigrants from traffic-light-only countries dither, they become less and less safe. However, with traffic lights a similar volume of traffic seems to me to move slower, especially when the lights are close together, and not well co-ordinated. After all, with roundabouts SOMEONE is moving.
Roundabouts MUST be large, wide, purpose-designed, have a limited number of exits well spaced, and have good visibility on the approaches, of the other motorists already on the island. Judgement of your approach is important.
They are not good when they are 'aftermarket,' too small, too many approaches, and have poor visibility.