You can use base R but (unless something has recently changed) not all packages are going to work. I also program in D - including interacting with R - and that won't currently work.
I have compiled numerous R packages as well (dplyr, ggplot2, FactoMineR) and they all work fine on ARM. I agree that you may face issues when it comes to packages relying on JAVA, but otherwise never seen any other problem so far on ARM.
