It has multiple novel ideas, such as generating a syntax tree of typed Lisp code as it is being typed in on the keyboard, which allows it to automatically check and validate symbol spelling and indent code based not on regexes, but on the actual Lisp code that is being edited.
In .NET it's even advanced to the point that the official C# and Visual Basic (and maybe others) compilers expose this functionality themselves, so that the IDE doesn't have to implement its own parser that may or may not understand things the same way.
Contrast with, e.g., working with Scala in IntelliJ, where you just have to kind of get used to the fact that the IDE will occasionally insist six ways from Sunday that your working code couldn't possibly compile.
It has multiple novel ideas, such as generating a syntax tree of typed Lisp code as it is being typed in on the keyboard, which allows it to automatically check and validate symbol spelling and indent code based not on regexes, but on the actual Lisp code that is being edited.