[jwr]

Really? I found that it's fine when all your data is lists or matrices, but it becomes increasingly terrible if you want to process structured data. Maps (associative) have been added late and in a half-baked way, using them is a pain. The way macros are written is pretty bad syntax-wise. There seems to be little consistency in terms of which arguments come first, so composing functions into pipelines can be awkward. Variables in "With" and "Module" cannot refer to earlier bindings, so I end up with multiple nested With/Module statements. Also, "Module" for lexical scoping, really?

Also, I never managed to achieve any reasonable degree of code reuse in Mathematica. Most of my notebooks are single-purpose.