It takes a while to get used to varifocals, which entails you moving your head or eyes to be looking through the correct part of the lenses. But once done, much better than turning a knob. If for example you are driving, looking long distance, what when you need to look at the speedo? Or looking at computer screen and need to see your keyboard.
I got Essilor lenses which were expensive, Bht 16000 for the pair, but are superb.