Warning: Unless you are experienced with python scripting, this course will NOT be quickly finished. Exercises are solved by typing (or pasting) in your python functions. The website supplies the input variables and runs any additional functions (such as looping your algorithm 1000 times). Often you cannot see the input variables or the additional functions applied, which can make troubleshooting difficult. Typically my first few submissions would be wrong; the code worked on my laptop but not on the website. It was difficult to track down the incompatibility or my error, since I did not know what the website was trying to do.
There are four parts. Part 1 is simple and easy, typically 1-3 functions per exercise. Part 2 starts to combine more functions towards the end. Part 3 and part 4 took me probably about 8-10 hours of work each, with the reported aggregate success rates on several exercises between 10-13%. It wasn't uncommon for people to comment they'd spent days on a single exercise (there are about 10-15 exercises per part). Occassionally someone will post answers to the exercises in the comments, but this is rare. Usually, you're on your own until you figure it out. You can read ahead, but you get no points until you go back and complete missing exercises. Once you complete an exercise, a solution forum opens where you can read how others did it much better than you.
Nevertheless, if you google (constantly!), spend many hours, and ask questions in various fora on the internet, you'll eventually find a solution. Along the way, you should be ready to tear out your hair over your code being repeatedly rejected as wrong. Apparently this latter ritual is also a measure of your quality in bioinformatics, since everyone who works in this field must be prepared to endure the grief of inexplicably failing code, persisting until a solution is found. So the frustration is supposedly part of the learning process.
Ultimately, this is how you will learn what your code is doing. You dive into it with pdb and check everything at every step until you understand the code. It can take a few minutes to an hour, but usually you do this anyways in order to troubleshoot.
Outside of the step-by-step function of your code, the broad goals of what you're doing, the aim of your algorithms and the biology, are mostly well explained. The text frequently invites you to stop and think, which for me meant stop and read others' comments, since some people are very good and post some enlightening commentary, which became part of my education. Every part has a couple optional excursions where you're debriefed on historical or related knowledge, which were actually surpisingly fun to go through. It was nice to read short, interesting sections without the pressure of a looming exercise to cap it off.
There is however no pressure. The exercises are not on a deadline. The quizzes can be repeatedly attempted until you have a 100%, with about half the questions never changing, and the other half typically only changing the numbers. Can't comment on the videos as I never watched a single one, just did the Stepik exercise program.
This course is marketed for beginners, but there's a big caveat with that (hence my 4 stars for that deception).
I began with a warning, so I'll end with a reminder of that warning:
Constructing your coding is not well explained. You're given a goal that's usually clear, but the "how to reach that goal via python" is almost always entirely up to your programming intuition. Your biology knowledge won't help you at this in any way. If you suck at programming / never scripted before, and you're looking to have your hand held through python, then either don't do this course, or maybe make sure you have the recommended codeacademy accompanying course for Python. I didn't do the codeacademy course, so I can't vouch for that, but maybe it will help. I know from others' comments on the exercises and my own experience that this can take over 10 hours for either part 3 or part 4 if you don't know what you're doing, and at times, specifically regarding errors in your code, leave you at a frustratingly complete loss for how to proceed, where you're on your own to figure out how to get your code working.