Realistically speaking, in Audit at least, your first 2-6 months are going to be doing the most basic audit work with things like the famous "ticking and bashing", reading through finstats, and substantive testing (ie. agreeing supporting documentation) but then as you do these very basic tasks, you begin to understand and appreciate why we do those things, the risks associated with each section of the balance sheet, the consequences of overstating/understating, and the 'best practice' way that some transactions should be recorded. At first, when you find problems or mistakes you'll flag the exception for a more senior member to look at, but like I said, once you understand things a lot better, you'll be able to determine whether or not an exception is worth adjusting, or if there are even more serious potential risks which were not originally noted in the audit scope.
As a non-graduate, you will obviously face a much steeper learning curve whereby you are learning both on-the-job practice at the same time as learning the fundamental audit principles and concepts at uni, but by the time you reach your 2nd year of studies, the benefits will start flowing through.
For example, at uni recently we're learning about the basics of costing and transfer pricing (yes I know this is very basic to a graduate!), but then as the teacher explains it, for every scenario and situation for various divisions oncharging each other and so on, I can think of multiple examples from real life experience which it relates to. I'm someone who learns alot better when I can link a theory with something I've seen in the real world, and as a result, I've found Accounting and Finance at university this year so far considerably easier to follow than I did a year ago, when I started off doing full time uni study without commencing my full time work/cadetship yet (and yes this probably gives away which firm I work at...)
I'd really go into more detail but I'm off to watch TV =] ... but despite what many people say, you really do get out what you put in. If you're willing to give it a shot and try your best to learn as much as you can, you will definitely be rewarded (not necessarily just financial). The experience you get as a cadet is very different to a coop/vacation student's exposure- but that doesn't really belong in this discussion. I'm only mentioning it purely because if you're going to ask people their opinion on cadetship work, don't ask someone who hasn't actually done it as a cadet.