TL;DR Rosario has industry experience, so that's a plus. But that comes with quite a bit of arrogance, inconsistency, and poor awareness. There's been some enjoyable lectures, and I've had worse professors. Rosario has a ways to improve, but for now, learning doesn't correlate to getting a good grade, so taking R-cubed may be more pain than it's worth.
--------
The class is weird. "R-cubed" is a friendly professor, but looking back, his class was not very useful. His lectures were not very relevant nor helpful. and he penalized students for not attending. I scored 2 stddev above median in midterm and fully expected an A in the class, but somehow scored below the median on the final, due to some very very strange questions that I could only assume were lecture-only.

He also has a poor attitude on Piazza, even referring to students as "entitled" when they ask for clarifications on his very confusing projects and examinations. He doesn't seem to recognize how his comments could be detrimental to mental health during the stress-packed finals week. He tries to be helpful, but is a flawed human with a lack of self-awareness in educating.

To his credit, he is a newer professor who's been in industry a lot, and I appreciate that he has such high standards for his students. I would be wary about taking his class, but it's pretty good if you're self-reliant and don't mind inconsistent grading.

Professor Rosario likes to give hard tests just like Professor Eggert does, but unlike Professor Eggert, his lectures does not prepare you for such kind of hard problems. He goes through simple and easy concepts during his lectures but mentions little about problem-solving skills. To get an A- for this class, you must go to his office hours frequently and ask questions. To get an A for this class, I'm sorry but I believe you have to do many extra practice problems. Moreover, he does not curve the class based on the average but based on what HE THINKS THE AVERAGE SHOULD BE(not bluffing, he mentioned it more than one during class) so you don't really get a lot of curve benefits from hard examinations.

Professor was honestly the worst I've had in UCLA. This is not supposed to be a hard CS class, it was supposed to be a useful CS elective. BUT HOLY COW THE FINAL WAS MOST DUMB TEST IVE EVER TAKEN. GDI i feel like I learned nothing, but I use all the stuff I learned in the class at work (and I know what I'm doing). The test did not test my understanding of the material at all, it was a test to see who can regurgitate most bs possible. DO NOT TAKE THIS CLASS. (honestly you can learn postgres, relational algebra, and stream by yourself with youtube WAY BETTERTHAN ROSARIO).

This was honestly one of the weirdest classes I've ever taken. The class started out extremely easy...the first project was a joke (easier than a CS31 project) and the midterm was very straightforward and fair.
However, once we moved on from SQL and started learning about more theory-intensive subjects, the entire class went completely downhill. Our second project was an absolute shit show. For some people, just RUNNING the project took 10+ hours since we were dealing with big data...and while we did learn very valuable information about Spark, I feel like there would've been a more efficient way to teach us this material. Additionally, one of the things that annoyed me the most was that he would not give us concrete methods to approach a problem...he would say things like "oh it won't show up on exams don't worry about it" which was extremely frustrating as a student. His homework assignments were horrible...they made no sense and needed a lot of clarification (you should've seen our Piazza LMAO). Our final was also the hardest test I've taken at UCLA and half the material was from like 1 or 2 slides from his powerpoints.
Overall, this class was okay. I learned very valuable information (esp SQL) and would definitely recommend to take it before you graduate. However, this class with Rosario was just extremely frustrating because of the lack of clarification in a lot of his projects/assignments. Don't get me wrong—Rosario was a great lecturer and his slides were very helpful (I really loved attending his lectures and he was very responsive on Piazza). I just didn't like his assignments and the overall structure of the class.

The funniest part about this professor is when a student pointed out his mistakes on the slide, he explained that he was not the person who made the ppt. When he could not explain himself, he would say there are some different implementations. Also, every time he said this won't be on the test, do NOT trust him. If you have to take this class with this professor, god bless you.

I started out the quarter really looking forward to what Professor Rosario had in store for CS 143 because of his modern approach and industry experience, but ended up disliking him and my life while taking this class.

Projects:

Credit to him here, the projects are practical and interesting. The 2nd project is fairly vague but doable if you start early.

Tests:

He wanted to be like Eggert but honestly he couldn't. Eggert at least gives somewhat fair tests, Rosario's tests were the biggest load of BS. Especially the final, a huge test where he handpicked the most random stuff out of his lecture slides and made it a large portion of the test. The final was the one of the hardest tests I've taken here at UCLA and it felt like he made the test unnecessarily hard.

Piazza:

He seems like an okay guy in person, but he can be seriously mean to students asking FAIR questions online. I wasn't even a victim of this but monitored Piazza frequently and it felt like he was going on some weird power trip.

Overall, I wouldn't recommend him for 143, it's not the worth the stress and the hassle. This is the first time I've felt compelled enough to write a BruinWalk review about a professor. He's clearly a smart guy but out to get students to fail his tests.

I was recommended this class specifically with this professor because he was supposed to be "amazing". This couldn't be any further from the truth. He has roughly 100 slides a lecture to go through at 8 AM in the morning. The slides are actually dense and whenever he was asked to explain something he always had no clue how any technical stuff really worked. Seems absolutely incompetent in any theoretical concepts to the point where he had to "get mad" and just move one due to his lack of knowledge. His homework and projects were fairly reasonable but were exceptionally vague. Anything you would ask on piazza would always receive a ridiculously sarcastic and demeaning reply. Never have I seen this much god damn toxicity in a piazza forum in finals week. His midterm is exceptionally long for the time given to us. The final was absolutely absurd. It seems like he just sat there the night before the final and specifically chose the topics that he said weren't going to be on the final or was incapable of being able to explain during lecture and designed a test around those concepts. Is he a good person in normal life...who knows? All I know is he needs to change how he goes about his teaching or just stay in industry.

Rosario at first seems like a chill guy and I feel like I learned a lot of practical stuff in the class. Midterm was very reasonable. But his final was the biggest load of BS I've ever seen. He pulled the most random stuff that he had only 1 or 2 slides on and made them worth a lot. Decided to test us on the most niche stuff rather than meat of coursework. Also kind of a weird guy, he would get angry when he was wrong, and it always seems like he was trying to flex his industry experience. I would try to avoid him, but it's not the end of the world big you have him.

Course Material: very dense, some useful, some a waste of time. This course covers so many different topics at a hastened pace. His lectures are powerpoint based; each are ~100 slides and each slide is pretty dense in content. In addition, you also need to read the textbook for certain chapters, which is also pretty dense. Much of what he covers is useful and practical, but he also covers some obscure and unimportant stuff. Try your best not to skip lecture if you can, or else you can fall behind pretty quickly.

Projects: time-consuming but otherwise reasonable and practical. There are 2 partner projects, each divided into an "A" and "B" part; i.e. (1A, 1B, 2A, 2B). Part A of each project is easy and are really warm-ups for the "real" work that constitutes part B. Part B comprises the majority of the time and work for each project. You are given 2 late-day passes (i.e. you could submit 2 days late without penalty) for each project, and there is no other late policy. I advise to start as early as possible on the projects (particularly the Part B's) and to use late passes on the Part B's.

Exams: I found the midterm reasonable and the final a bit challenging/unreasonable, in part because of the sheer amount of material covered in this course. Anything in lecture, even seemingly unimportant and obscure topics, are fair game for the exams. As of this post, midterm average 66%, final average TBD.

Homework Assignments: reasonable and graded mostly on completion. There are five homework assignments, and he drops the lowest homework score.

Also, if your Final Exam "letter grade equivalent" is higher than your midterm "letter grade equivalent", he replaces your midterm grade. Likewise, if your Final Exam "letter grade equivalent" is higher than what would be your final grade, then your Final Exam grade becomes your final grade.

Overall, I found this class to be challenging compared to other CS electives, in part because the course is very material-dense. I did find the exams (the final in particular) to be unreasonable, and I do agree with the sentiments of other reviewers in this regard. However, the professor does seem to have good intentions, by introducing more practical and useful applications in this course and by trying to grade as fairly and consistently as possible.

He is probably one of my favorite professors so far, I think I took advantage of the office hours a lot and also spent a great deal of time studying. My goal is to learn as much as I can, so I don't think this class is as bad ( maybe because it fits my goals better). I do believe Rosario is trying hard to make this a good class, and it is hard to avoid many issues when it's still being taught for the second time , and we all need some understanding at some point of life. Also, I do think the exam was hard, but that doesn't necessarily mean the grading would be bad . Overall, I still thank him a lot for everything.