Cons
Footprint - The library is 500 KB in size (using mod_gzip could be reduced to 150KB). Loading time would is high for home page on web.
CSS – very easy to get lost. It is difficult to find correct class names
HTML – full of divs and overly complex generated code. Difficult to debug even with FireBug.
Modified GPL 3.0 licensed. Free for open source applications but paid for commercial closed source applications.
Using ExtJs leads us to believe that the GUI would kind of desktop and rich. Customization is not easily achievable.
Loading even simple things requires few lines of coding which is simpler in plain html or jQuery.
Debugging is not very easy. Only GWT has bit better debugging in hosted mode among javascript frameworks.
It is not possible for the user to bookmark a certain page . Since the objects are rendered by DOM manipulation, page can not be indexed by search engines
Need quite experienced developer.
I'm not sure how to use this without the entire display being EXT. I would prefer something that could integrate into what we already have.