I like that it is easy to use, has many options for customization, can be used in both web-based applications as well as mobile apps (iOS & Android). It's free! The only thing i dislike about this toolkit are some of its limitations which make integration more difficult than necessary sometimes when you have no clue what could cause these issues.
If anyone wants an application development platform with excellent performance then look into QCOBJECTS - their API allows your app or website to run