There's no longer a well-defined syllabus listing all the stuff you need to know - so it is really important to do extra reading as well as attending all lectures/ supervisions/ labs. Also, there are no set answers to exam questions and no markschemes - making revision really difficult. University is no longer about learning to pass an exam (as it is at A level), but instead a much vaguer assessment of your abilities.
Also, no resits and constantly assessed practicals means that you can't afford to slip up at all - if you fail, you're out. It's so important to keep on top of the work throughout the year, I started drifting behind in the first term and it took solid studying for the whole Christmas vacation to catch up.