If you have any interest in low-level programming, this is a good course, and leads on to COMP9242. The exam was really easy overall, but this may have been because it transitioned online. The last two assignments really need you to have read a substantial amount of the OS161 codebase to do well, but having done so it's relatively easy. I advise you to set up a good IDE on your local system to do the assignments, as doing it through VLab or SSH is painful, and it's very difficult to navigate such a large codebase without an IDE with decent features (I recommend VSCode - once it's set up you can very easily find what you need). Much of the documentation is in the code as comments, rather than in a separate document.
The content itself goes through an introduction to concurrent programming, and how OS's are made, along with the surrounding environment (so things like how I/O happens, interrupts, multiprocessing). Most of the content is relatively straightforward, and is pretty easy to understand as long as you pay attention to the basics. If you follow the lecture content, or can cram well, then most likely this will be a WAM booster. Do we warned though, the final mark is a weighted geometric mean of your assignment and your final exam mark, so if you screw up one of the components, it may affect your overall mark substantially.