What else is cool about GNU Smalltalk?
First of all, it is free software. This means that you can play with it and understand how it works, break it and understand why it broke, fix it and enjoy having fixed it.
Compared to other Smalltalk implementations, GNU Smalltalk is very different in one aspect: it is pragmatically designed to be a tool rather than an environment. It complements other tools that you use in your daily work, without any pretense of completely replacing them. This also provides a smoother learning curve for people who know other scripting languages such as Python or Ruby.