I worked on one of the larger Smalltalk project in the late 90s, an application of the HP OpenView Network management suite. Using Smalltalk was in principle very productive,non-Smalltalk people were always amazed seeing us changing code in the debugger and just continuing running the application without a restart. The problems were rather coming from the lack of integration with standard versioning systems and the monolithic nature of the Smalltalk image concept. Later on when ruby started to become popular, which in my opinion was very similar to Smalltalk, but had a module concept and not a monolithic image concept.