I found AngularJS very readable and was able to read it during my commute over the course of a week.
However: I read the documentation first.
I think you'll find if you give it a chance, you'll find that AngularJS has excellent documentation.
Someone put a lot of effort into taking what is organised for implementation (code) and reorganising it for users, and it was something that was very much appreciated.
For example, you should look at this:
* http://docs.angularjs.org/guide/di
There's a very subtle piece in there about how AngularJS figures out what the dependencies of a function actually are, and understanding that piece is key to understanding how much of the AngularJS code is written.
I did start diving into angular source code, and found it quite readable. I simply read it from top to bottom, and it is quite well understandable this way. I read it one function at a time on my ipad whenever i needed a break, and i think one could manage to read it all in one or two weeks (depending on how much free time in the week you've got)
However I cannot comprehend Angular's source code on github. Can anyone give me pointers on where to start reading it and/or how it's organized?