
I like the flexibility the framework provides. I've mostly used Cocos2d-x which allows you to create your games using C++, Lua and Javascript.
Using the Javascript bindings you can literally create a flappy bird clone in 2 hours or less (assuming you already have your audio and graphic assets). The JS development cycle is fast, lightweight and allows you to test your code in 2 seconds or less (depending on your computer capabilities)
If you would like to use Cocos2d Sprite Builder you could also create games easily using the tools bundled with framework. Review collected by and hosted on G2.com.
The side tools provided by the framework are not as integrated as it should yet. They've deprecated many tools before being able to adapt it to the current needs (like Cocos IDE and CocosStudio).
Also they've just launched the Cocos Editor, that overlaps some feature of other tool calles Cocos.
The tool strategy is not clear yet. in 2015 they've announced that they will change the name of the Cocos2d-x framework to just Cocos, they've launched the Cocos tool, but Cocos.org site still only available in Chinese. They still launching tools outside the Cocos integrated tools even when they said they wont. Review collected by and hosted on G2.com.