This class used to be required for those thinking about pursuing a structural/geotechnical related track. I will be very clear: this was the most valuable class I've taken at UCLA as a C&EE major. This also happens to be among the most challenging classes, but it is extremely rewarding and you are learning from the best. I took this class with Professor Stewart and Professor Hudson, who both make this experience very enjoyable. I do not know who else can manage to fit in unique non-textbook homework, interesting project, proposal & report-writing workshop-style lectures, a field trip to an ongoing project, and an extremely comprehensive class on foundation design. To students who decide not to take this class because its "hard", you are missing out on the reason why you attend a school like UCLA.

Not to mention that if you do very well, you will stand out and will (probably) be offered a job.

Great class and great professor. The homework starts out really long and tedious, but they get much easier as the quarter progresses. The course reader is really helpful for studying for the exams, since they are mostly conceptual, so do try to read it. Stewart actually did a really good job in picking out the material he put in the course reader, and it's totally worth the money you spend on it. The group project will kill you. You can work for years on it (like my group did) and still do terribly. He grades it very hard, but he'll give you a fair final grade, so don't worry too much about it.
You will learn a LOT more than you expect in this class, even if you had a hard time in CEE 120. I feel like I learned everything about soil mechanics from Stewart, and I'm pretty sure I'll never forget it. He's a nice guy and he will make sure you understand the material rather than just teaching you how to apply formulas. I'd also recommend that you try to go on the field trip that he organizes every quarter because he puts a lot of effort into making it possible and he makes sure you can see the relevance of what you do in class to the "real world".
Big mistake if you don't take this class. He's a professor that everyone should have the opportunity to experience.

121 is a lot of work, but Professor Stewart is a great teacher. You learn a lot during the course. He covers a lot of usefull information and teaches from a practical perspective because he practiced before becoming a professor. The grade is 20% midterm, 20% homework, 20% final project, and 40% final. Overall, excellent course, very worthwhile. He is one of the best teachers in our department; if you have the chance to take him you should.