Could be considered one of the hardest introductory module in NUS. There is a very heavy workload. 4h solely on lectures and 2h on tutorials. On top of that you still are required to do coding task, which could take up literally 1 whole day.
You would start off with the theory of recursion, and some basic program that limits your answer to using solely recursion. This encourages you to think in a different way - a way where programmer should think. This way of thinking would help you in your future career as an programmer/computer scientist.
All in all, CS1101S is definitely memorable for me, and its definitely much better than other CS1010 modules in terms of the concepts we learnt.