[hadley]

There are three areas where I think R is the clear winner:

1) An IDE for data analysis/programming: RStudio

2) Easy way to turn your analyses into reports: knitr

3) Easy way to turn your analyses into interactive webapps: shiny

(I also think R wins on visualisation and data manipulation, but I'm biased ;)

[peatmoss]

R absolutely wins on visualization and data manipulation. I'll spare you the immodesty :-)