I've used various editions of the OOH for 20 years. It is a central tool for those looking for information about careers and jobs out there ... rich detail, much data on occupational projections and salaries, but not to the point of being mind-numbing (which would be easy to do.) On the other extreme, much of the career literature & reference material is simplistic, basic, or paternalizing and the OOH does NOT stray into over-simplifying the world of work.
While most/all of the latest OOH is available on-line for free, I still purchase a paper copy every two years. It is THAT valuable to have on my bookshelf for the extensive work that I do with people who are in the beginning or middle of their career development.