“Shorter operator names sounds like a pretty superficial feature. But they mean you don’t have to break lines so often, which in turn means that you can see more of your program at once. The biggest win is in the names of operators that tend to be outermost in nested expressions, like map, progn, and lambda.

Operator overloading should be subsumed in the more general question, how should you define a new type?

Macros and implicit local variables just don’t seem to work well together. Any language that already has implicit local variables will run into trouble if they try to add macros.