I’m helping out with a beginner’s R workshop and I might say a few words at the beginning about what I like about R. There are three big things, really.
First, I like how you manipulate output in R using the same tools that you manipulate data. So if you wanted to round the values in an ANOVA table, you use the same function that you would use to round values in your data set.
Second, you have a lot of control over graphics output in R. You can control the size of the graph and the size of the margins of the graph, the values that you place on the axes and where you place the axes themselves, the size and colors of symbols on your graph, and many many more details.
Third, you get access to some of the most current statistical methods with R. Most graduate students in Statistics want to see their new methods used, and they do this by writing user contributed libraries in R as part of their dissertation. It takes a while for programs like SAS to get someone internally to program these methods.