I love ExtJS, and still use the version 5. This post is very true for me too. I didn't upgrade to version 6 because the new license system and the last versions

I love ExtJS, and still use the version 5. This post is very true for me too. I didn't upgrade to version 6 because the new license system and the last versions is still very unstable in my tests. But I will really miss the JSON-way of creating interface. With Xtypes everything is defined as a json object. And is incredible the customization options of their components. Other thing that I will miss a lot is how well integrated is the presentation components with their data layer.