Aside from the development environment, I find the language itself also very elegant. While the evaluation rule for binary messages can be very counterintuitive

Aside from the development environment, I find the language itself also very elegant. While the evaluation rule for binary messages can be very counterintuitive (always left-to-right, so 1 + 2 * 3 = 9), the rule is simple and easy to learn. Keyword messages are something else that I think is just very nice, and the evaluation order of messages (1. unary messages, 2. binary messages, 3. keyword messages) often lets you create large composite expressions without the need for (m)any parentheses.