he is definately not the easisest professor you would get here at ucla, but he's ok one.
if you only study his practice exam posted on the class website, expect to get c or below(or maybe not if you are smart enough). KNOW THE CONCEPT from the notes he post, it can be very hard due to overly used sigma and other mathmatical terms if you are not a math person. If you mastered the concept he posted on the website and do the practice test, you will be fine with his exams which is more like to SAT style questions where you dont have to think but apply the concept. Theres no point of avoiding him, even if you take the same course with another professor only 25% will get A 25% will get B and rest will get C or below. If you cant be those 50% in liao's class im pretty sure you wont be in top 50% to other professor's 41.

TIPS: dont panic when you see the problems that were not on homework or your practice exams.. because the answer will be kinda obvious. if you roll the dice ten times and the number of times that you will get 3 will definately not be .9000
half of the test questions have obvious answers.

Liao was an incredibly frustrating professor. I don't know what the other reviewers are talking about, but his midterm is 100x harder than the practice midterm, as is the final from the practice final. This quarter he gave us the final from the previous quarter, which is a slightly better indicator of the difficulty of the exam but overall not helpful. He's one of those professors who teaches you problems one way and then expects you to know how to do them a different way that you never even covered in class.
He has an accent, but if you're used to hearing accented English, it shouldn't be a problem. He basically rewrites his online lecture notes verbatim on the board during lecture with maybe a few extra example problems thrown in. The homework problems are absolutely no indicator of the difficulty of the exam questions, even the "starred" ones.
I think part of the problem for me is that he doesn't teach the class with an aim towards what you "need to know," if that makes sense. He just gives you everything and it's up to you to pick out the formulas and such that are important. He also gives you no context for what you're actually trying to do. I took AP Stats in high school, and my professor would teach the class in terms of 'population' and 'sample,' so you kind of knew the difference between things intuitively. Liao doesn't even really use those terms.

Basically, if you can avoid taking him, do. If not, I would recommend trying to find a tutor or some sort of supplemental help.

his midterm was hella easy, got 30/30. Midterm was exactly like the practice midterm he gave with different number, but the problem comes when you take final. I just studied practice study guide for final as his midterm was just like the practice guide, and he also stated that the practice guide will be the good study guide for final exam but NO. His final exam was 10000x harder than the practice guide with so many advanced questions. well... good thing that he curves the grade but if you dont study with tutor which cost 50$/hour, dont expect to get 70+ in his final exam. GOOD LUCK AND HAVE FUCKIN FUJN