The problem with R is that it's just not a very good programming language. It's great for interactive analysis, but dismal for building higher level abstraction

The problem with R is that it's just not a very good programming language. It's great for interactive analysis, but dismal for building higher level abstractions. It's like the PHP or MySQL of the data analysis world. Data types get magically converted all over the place, the global namespace is just a giant playground for every module to pollute, it has something like 5 different object systems all with subtle differences. All the defaults that are set for the convenience of interactive use undermine any kind of reliable use for building on as a platform (for example, the "simplification" concept where a 1 column data frame often magically turns into a vector). I've forced myself to use R intensively for a couple of years now, but I must say it's still a relief every time I bail out and get back to a "real" programming language.