Agree about beauty---but I think the real genius of ggplot2 is the grammar. After using it, I think it becomes easier to think about data graphically and then quickly generate the visualization you have in your head. ggplot2 alone is a reason to switch to R.
Yes I actually meant beauty more in terms of the code rather than the graphs. Even the documentation is top notch.
It renders a lot faster if you change the x11 type type to Xlib, e.g. X11(type="Xlib") before displaying the plot.
Sadly I've turned away from Ggplot to Lattice in a major way simply due to the speed. If you're plotting a significant amount of data then ggplot can easily take 5 or 6 seconds to plot a panel compared to the nigh instantaneous Lattice library. Which I'm fine with really. Hadley Wickham is doing interesting stuff with ggplot that shouldn't be burdened by racing Lattice. It does mean I'm less likely to use it for exploratory data analysis though.