One feature of JCL which I think is cool, is that whereas on Unix processes inherit file descriptors which are numeric only (and hence few applications know what to do with anything other than FDs 0-2), in JCL you instead have DDNAMEs which are 1 to 8 characters. I think, if Unix had alphabetic names for inherited streams rather than just numbers, you might see more Unix programs supporting more than three inherited streams.
Another feature I think is cool is catalogs. A database mapping dataset names (file paths basically) to the filesystem volume (disk or tape) on which the file lives. You can move a file to another disk or to tape without changing its name/path.
(Strictly speaking both of these are features of the MVS operating system as a whole, not just JCL per se, but JCL is one of the main interfaces to them.)
JCL is just another scripting language. I found it fun. I did all the JCL for my group's production jobs and commented the hell out of the esoteric issues to help Operations triage things. A small, well-planned effort prevented a crapload of, well, crap.