In my academic career, I have found that it is pretty difficult to assess the quality of a degree before enrolling. Usually only during the course of your study do you learn what the actual quality of the degree is, which are the best schools, and what your chances in the job market are going to be like.
Getting in touch with students studying at the university is usually pretty difficult if you're not enrolled, and i don't really trust the responses of the professors (who have a vested interest).
What would be a good way to judge the usefulness of a degree? And how can you reliably assess the chances of getting a job with that degree?
Many universities will publish statistics on how many of their graduates are employed or in further education within X months after graduating. If you're only concerned about getting a job, then that's probably your best source of information.
That said, in the end it depends on you. People get jobs with crappy degrees and fail to get jobs with really good degrees. Whether you'll be able to get a job in your chosen field will depend on what exactly you do for your degree.
A good opportunity for improving your chances of getting a job after you graduate is to do an internship while you're at university. Many universities have job centres or similar that can help you with that.