TP3 has very rich scripting support. Not yet documented, but the intrepid can begin some preliminary explorations though ⇧ ⌘ W > resources > birch.js, and I’m sure that full documentation will follow, at some stage.
The core of the application is written in JavaScript, and the natural choice for its programming interface is therefore JavaScript rather than AppleScript. (You should still be able to find the FT discussion thread where the problem of maintaining two parallel APIs for these applications was discussed - the mood was that it would be sensible to just maintain a JS interface, with a bridge from AppleScript for calling the JS code for those who prefer to do it that way.
Your existing AS scripts will continue to run from copies of TP2, and learning a little JavaScript will enable you to write faster scripts, with even more reach, in TP3.
( I do remember pausing for breath before jumping into JavaScript from AS, so I sympathise, and I can assure you that having made the leap, JS turns out to be much easier and more pleasant that AS in several respects (easier records, richer libraries etc). It’s also more omnipresent - more useful not just on the web, but on iOS too (Drafts, TextExpander, and various other apps).
(I now do all of my OS X scripting in JavaScript for Applications, incidentally, after years of investing quite heavily in AS )