Excellent learning tool Content is designed simply to increase readability, and attached to examples that help solidify the principles. Very organized and navigating courses and content is smooth. Fair customer service that strives to evaluate needs on an individual level.

Great interactive learning tool Great interactive learning tool, works like duolingo but for maths!

Kind of a cool system Kind of a cool system. I did not stick with it cause life is too busy. When they charged me and I cancelled just after they were flexible about giving a refund. They only do that once so don't be sneaky!!

Disappearing classes Although the classes are interesting and the math is (sometimes) well explained, there are also a lot of issues with Brilliant: *Classes disappearing in the middle of doing it. Algebra 2 for example *Classes skimming through essential piece of information, e.g. Introduction to linear Algebra. I'd really recommend a mix of other solutions if you want to further your understanding of mathematics. Khan Academy & 3Brown1Blue (and many other free resources) provide better explanation and have the same level of interactivity.

Good for children (i guess) The idea is cute but imho accomplishes nothing. It tries to "gamefy" the learning experience but just muddles the learning in the process. I can see this being a fun way to learn about our world for small children or maybe young teens, but the site is definitely marketed towards all age groups. Just reading the wikipedia article about whatever subject you want to learn will most likely get you a better grasp on the topic than spending money on the premium subscription, which a lot of it is being spend on making 'cute animations' and keeping the app running. I have yet to come across actual exercises which require any deeper skill whatsoever. If you have a small child at home which wants to learn about science and the like in a playful way or if you are an adult and want to feel like you are learning something new on your commute this is probably not something bad. For me though this feels like another attempt to make an app for something which does not need it. Buy a book instead.