The problem with OO - and this applies to Smalltalk too - is that class hierarchies are a bad fit for a changing business environment, being hard to refactor wh

The problem with OO - and this applies to Smalltalk too - is that class hierarchies are a bad fit for a changing business environment, being hard to refactor when previous assumptions change: inevitably some new case will come along which requires changes to the structures that were originally defined, and OO is harder to deal with in that context. That said, I do think OO is good for problem areas that actually have fairly static interfaces, like GUI libraries, for instance