EDIT: Moreover, your quotation about performance is from the section on "model complexity", where the original authors were far too generous to Angular. The model of an Angular app is tightly coupled to the Angular system, whereas a React app model is just a POJO.
All of the things that seem useful about Angular become a burden at scale. ng-repeat is my favorite example: try repeating more than a few hundred non-trivial components and you'll quickly choke the browser. You end up having to spend most of the application development time figuring out how to do things in a way that doesn't make Angular too upset.
I had spent a couple of years prior working with WPF which is MVVM based, so I was already familiar with that way of thinking, which maybe helped me out.
I think Angular 2 is going to catch a lot of people by surprise, if they haven't been keeping up though. It's all component based so I've been restructuring my apps so that everything is a component, which means that an upgrade shouldn't be too painful!
I've seen a number of Angular apps though where directives aren't even used, and those people are going to find upgrading to 2.0 pretty much impossible without an entire rewrite I think! Maybe I'm wrong!
The process was also easy for my coworkers, granted they had someone to ask questions from.
I honestly cannot understand this criticism of the framework being hard.
I have no experience with React but what little experience I have with Angular makes me think I would come to the same biased conclusion... Angular was just a massive pain to work with if it's basic functionality didn't match your use case. Of course, I was probably "doing it wrong" but that only speaks to the "bumpy road to mastering Angular" the author speaks of.
That and didn't Angular basically get overhauled recently, or is slated to?
foreach(Feature f in AngularJS.Features) { RIP(f); }
Here are some other golden nuggets:
"React makes it simple to control the performance. If you implement shouldComponentUpdate, you can choose which comparison you prefer - model or presentation." (Oh, "performance" have never been simpler.)
"React gives you the freedom to choose, without the performance penalty. The outcome really depends on whether you're a good coder or a bad coder." (So Angular is slow regardless of you are a "good" or "bad" coder, but React performance depends on you "goodness" - check)
"When something doesn't work in Angular directives, one option is to re-write the code in a different way because there's so much magic going on." (Or you could - like try to find out why something in your directive doesn't work?)