@thor M2 was similar to Pascal (they were brother languages, after all). One thing that made it, IMHO, unsuitable for real-world use was that all the keywords had to be typed in uppercase. I guess it was a poor man's form of syntax highlighting.

It was very good for learning because everything in it was neatly organised and it made understanding the program and checking its correctness by hand very easy. For example, functions and procedures had a slightly different syntax. All other languages don't distinguish between them. Functions return a value while procedures are just executed for their side effects. Modula-2 would have given you a syntax error if you had used them incorrectly. Cue to modern languages where everything is a function and you don't even have to declare a return type if you don't want to.