As Silver Knapper, I did Aero Eng, graduated back in 1997.
I have not long finished my ATPL's, September in fact, and to be quite honest they are nothing to worry about. I was in exactly the same boat as you this time last year, apprehensive and wondering what to expect.
Personally I found the knowledge that I aquired during my degree was of great benefit, in terms of getting a head start, especially on the technical side, for example Principles of Flight, Instruments, Gas Turbines, Pistons and subjects of that nature. After doing Aerodymanics and Flight dynamic and Performance, Principles of flight was revision, however on saying that, I found my self learning an awful lot too! Every now and again I would find myself having a greater understanding of a certain subject, that perhaps I was a little sketchy on before, simply because it had been taught a slightly different way.
As these guys here have said, the ATPL syllabus requires you to aquire a great deal of knowledge, and be able to remember hundreds of facts, where some will be of use, and some will not. In comparison to the degree course, I would say it is simply different. Whilst studying for my degree, I spent most of my time doing assignment work and project work, which for me was a different type of stress for what the ATPL's gave me. The ATPL's is constant study, I found myself studying pretty much every day for the during of the course. My life was pretty much on hold for 7 months, it is just a question of going for it.
As we were told as a class at the beginning of the course, you will get out of this course what you put, and after finishing it, I could not agree more. Obviously some people will struggle with certain subjects, however, if you put the work in you will be ok.
Anyway I think I am swaying off at a tangent here. One thing I would like to say about the examinations is that some of the questions are written in such a way as to catch you out. As well as knowing your stuff, you need to have an eye for detail, in terms what the question is actually asking you, and how to go about answering it. All this will come when you start the course, and when you start going through the feed back questions and having progress tests.
Good luck, I am sure you will be fine.