Stumbled upon these videos, and I thought I'd repost them here, because they also express my pain learning Japanese.  I agree that there is a case to be made for Japanese being the most difficult writing system in the world.  For precisely the reasons the video mentions.
Chinese has thousands of characters, but each character only has one pronunciation, so although the task of memorizing thousands of characters may be daunting, it's at least relatively simple.
But Japanese....? Kanji are so complicated in Japanese.

Japanese isn't all bad, however.  The phonetics of Japanese are very simple.  So it's relatively easy to get to an elementary level or pre-intermediate level of Japanese.  (I considered myself, at the peak of my studies, to be somewhere in the upper-intermediate level).  Having lived in Cambodia and Vietnam, I now have new appreciation for how simple and easy Japanese phonetics are.
Despite the frustrations the video mentions about Hiragana or Katakana, they are actually pretty simple to learn, because they line up with the English sound system quite nicely.  You just have to learn which characters match the sounds that you already know.

In Cambodian or Korean, the writing system is based off of a lot of distinctions between various vowels we don't even have in English.  So I couldn't even get off the ground with those writing systems, because I couldn't even hear the difference between the characters.  (My ear couldn't hear the difference between Cambodian vowels, so I couldn't master the writing system, which was based on the vowels.)
So in that respect, Japanese is easy.

But to get to an advanced level of Japanese, you need to crack the Kanji.  And this is nearly impossible.  For all the reasons the video mentions.  50,000 Kanji, two-thousand of them in general use, on-yomi and kun-yomi readings for each kanji, and in most cases multiple on-yomi and kun-yomi readings depending on context.

I once had ambitions of studying history in Japanese.  But I remember the day I gave up.  I brought in a popular history book to try to study with my Japanese tutor.  (A native Japanese speaker who had spent all her life in Japan).  It wasn't even an academic book, just a popular history.  But we gave up on it when my tutor didn't know how to read much of the Kanji in that book.
If native Japanese people can't master the Kanji in history books, what hope did I have?

The Hardest Writing System! - an animated rant about learning Japanese



Kanji Story - How Japan Overloaded Chinese Characters