As you can read in the official description, “the goal of ggvis is to make it easy to describe interactive web graphics in R”. It combines:
> a grammar of graphics from ggplot2,
> reactive programming from shiny, and
> data transformation pipelines from dplyr.
ggvis graphics are rendered with vega, so you can generate both raster graphics with HTML5 canvas and vector graphics with svg. ggvis is less flexible than raw d3 or vega, but is much more succinct and is tailored to the needs of exploratory data analysis.
Find here a simple script with ggvis basics.