If you're a biomedical student or serious scientists then you'll have to perform some pretty complex linear and non linear calculations.
R is an attempt to provide a wide variety of statistical analysing - namely linear and nonlinear modelling, classical statistical tests, time-series analysis, classification, clustering methods and graphical techniques. The developers have chosen the S language as what they call the "vehicle of choice" for research in statistical methodology. The main strength of the program is that it can produce high quality, well defined plots including mathematical symbols and formulae. The aim has been to put control in the hands of the user although it has to be said, the user needs to know exactly what they are doing with such complex tools to get any real benefit out of it other than drawing pretty graphs. Since it's open source however, it's very open to customisation by it's users so if there's something you don't like, you can access the source code easily.
A very professional analytical tool that's strictly for experienced or Phd level scientists - beginners stay well away.