Now those hilarious bugs only happen at the REPL, which is a little better. If these kinds of bugs cause problems for you, i strongly recommend creating packages for your analysis/projects. It doesn't add that much complexity (with devtools, at least) and it does avoid a lot of these problems. Also, R packages require documentation, which is better than many other languages.
The test coverage issue is what originally prompted me to get involved -- I was evaluating different EM solvers and found a lot of crazy obvious bugs (parameters backwards or totally ignored). There's a lot of room for improvement on the quality front. MRAN and Tidyverse are thankfully making some headway.
Not completely sure this is what you mean, but you can certainly run install.packages("package") right in your code, doesn't have to be done interactively. Usually want to first check if it is already installed, like with require("package").
- documentation is all in PDF format
- can only install packages from the interpreter
- testing libraries not feature complete
- weird namespacing
- poor test coverage in popular packages
- no mature webserver