I've wanted to learn COBOL and so I jumped at the opportunity to learn it at my old job. I enjoyed it quite a bit because of the challenge of learning a 25+ year old code base with no documentation on a product that literally ran the entire company (it was settlement software for a clearing company). I enjoyed it but left for other opportunities. The problem with COBOL is I don't think you'll find just a COBOL job without having to know JCL or other mainframe languages/programs as those are important as well.