A hands-on comparison
A comparison between Apex and JET is made by redeveloping two Apex applications with JET. The experiences to build these applications with JET compared to the effort needed in Apex clearly shows the strong areas of both tools.
The applications I redeveloped were my entry for the Apex Dashboard competition, with a lot of charts and fancy stuff, without data manipulation. The other one is a small mobile data entry application that is used in tomato greenhouses to register the growth of the plants.
As a bonus the mobile application will be converted to a mobile app using Phonegap with offline capabilities.
The findings of this investigation can help you choose which tool is most suited for your needs.