I have. R is far less verbose and maps far better to data analysis. The Wolfram lang is far more expressive and powerful for symbolic computation. So basically, Wolfram for doing math Research, R for applied stats.
I have not. I started using R due to its open source codebase and ability to audit and understand exactly what its doing under the hood—being able to see how statistical formulae were implemented in code was invaluable in understanding and interpreting a package's analytical output.
R gives you a relatively simple set of tools that you can combine in powerful ways. The Wolfram Language seems to have a specialized function for everything, which is nice sometimes but it takes me longer to get started when doing exploratory data analysis, since I have to remember more nuanced stuff.
I absolutely love R. Once you get your head around data types and the 20 most important functions, you can do amazing things.
