Voyager 2 Images of Uranus

Voyager 2 images are probably especially featureless because they were taken during the solstice on Uranus. The continuous rays of sunlight had been falling on one of the planet's polar regions for many Earth years. And so this regime of nonstop polar daytime created a haze of methane in the upper atmosphere. By contrast, when you see photos of Uranus taken by telescopes during its equinox, you will see more defined atmospheric bands and clouds.