R is so incredibly powerful. I am taking two courses on it currently in my graduate studies. It's definitely tough to learn at first but once you get the hang of it it really is fun. I love that you mention what a pain Excel is when you have to change data and it can't just update plots like r... It can also work with GIS applications and analyze geospatial data which is so dang cool and is actually more efficient at some things than running tools in ArcMaps.