After downloading and unzipping one file you’ll get a set of well-known libraries (e.g. RequireJS, Knockout et al.) plus the library of the UI components developed by Oracle.
I’ve asked Geertjan Wielenga, one of the JET product managers, if it’s possible to replace one of the libraries included into JET with another one. He responded positively and pointed me to this blog that shows how to use JET with AngularJS.
I’d be interested to see if JET’s UI components can be used together with other WebComponents-based libraries like Google Polymer. The other thing that I’d like to see if it’s possible to replace the module loader RequireJS with SystemJS that supports loading modules of different formats (including ES6 ones).
A JET plugin for the NetBeans IDE includes a convenient debugger that can be used inside the IDE. Oracle will offer support for JET, which is important for enterprise folks.
At the time of this writing the JET Website reads “Don’t use it in production (except if you’re an Oracle Cloud customer)”, but Oracle will open source it at some point in the near future, so everyone can use it both dev and prod. If I’m not mistaken, this will be the first organically open sourced Oracle product. By “organically” I mean that it came out of Oracle’s own initiative, rather than out of the takeover of another company. Try it out.