For React, you should be comparing React + Flux to Angular.<p>The biggest problem with Angular is that it has a <i>very</i> steep learning curve, and writing bad Angular code is worse than writing bad jQuery soup.<p>- Using watchers/observers are encouraged, which makes control flow impossible to read for sufficiently complex pages. It effectively creates a potential side effect on any variable that can't easily be traced, and multiple watchers can casacade changes to eachother.<p>- Because of the way watchers/events work, Angular's digest loop implements a TTL, where it will keep evaluating watchers/events until there are no more changes, with a hard stop at $TTL+1. While this solves a lot of problems, it can make it very difficult to monitor state changes in the view, when a console.log/debugger/breakpoint will get triggered ten times as often as you'd expect.<p>- Angular has a <i>lot</i> of terminology[1], and each concept has its own set of idiosyncracies. When you combine this with the additional bootstrapping logic in Jasmine (and things like isolateScope), it ends up being very complex for a developer's first framework.<p>- Parent/Child relations in Angular are inferred from the structure of the DOM. This means you need to read your templates to figure out how your app is structured, and you'll end up with tight coupling unless you're diligent about your design decisions.<p>- It's very easy to let a lot of view logic slip into ng-bind and similar attributes. All of this logic should be extracted into objects and unit tested, but this means that a lot of the convenience of using Angular's declarative syntax end up being minimal at best.<p>- Like any framework -- expanding on what #quadratini said -- you need to use Angular's built-in libraries to do anything. While the syntax is reasonably similar, $timeout, $interval, $http, $q, etc all need to hook into the digest cycle, and this means you'll be wasting time figuring out when to call $apply or when to wrap a piece of code in $timeout just to get it to play nicely with Angular.<p>Angular is very powerful and not necessarily a bad framework, but based on my experience using it in a team environment for the past year and a half, unless everyone is senior-level at Javascript, you're going to quickly end up with a lot of hard to maintain, mediocre code.<p>[1] <a href="https://docs.angularjs.org/guide/concepts" rel="nofollow">https://docs.angularjs.org/guide/concepts</a>