Yes, it is worth the price in my opinion. If you buy the parts from Taylor it costs half of what the price is for the factory to do it (and that is not considering shipping charges!). It was during a phone conversation with Taylor that they suggested I simply order the parts rather than send it back to the factory for the upgrade. If you are upgrading a generation 2 2007-2009 ES (9-volt battery) it does not need to go back to the factory as no woodworking is involved. If you have a generation 1 ES from 2003-2006 (AA batteries) it must go back to the factory for the upgrade. There are three changes over the generation 2 ES:
1.) The new discrete circuitry pre-amp
2.) The new sensor harness with the single body sensor
3.) The relocation of your existing humbucking coil for the neck pickup (this was an accidental discovery by Taylor when redesigning the ES and makes a huge difference in sound!)
When I upgraded my 2009 714ce, I bought the parts from Taylor and then a Taylor tech rather unexpectedly did the install for me at a Taylor Find Your Fit Road Show for free at Wildwood Music in Coshocton, Ohio (where I have purchased three new Taylors and one new Martin over the last six years!). I had the parts with me that Taylor had sent me and I showed them to Sam Eakins, the Taylor tech, in order to ask him some questions... especially with regard to relocating the humbucking coil... and he asked if I was traveling with my guitar. When I said "yes" he insisted on doing the upgrade then and there. It took all of about 20 minutes and that included the complimentary restringing and polishing of the guitar that was taking place at this event. There was nothing difficult that happened and I easily could have done this myself after having watched Sam do it... but certainly consider having a Taylor authorized repair center do it for you. It shouldn't be that much labor as the time required for the work should fall well under an hour.
To me the newest generation 3 ES is warmer, more transparent, and better balanced (mid range is tamed). I find my guitar can be run "flat" into the board with the board channel flat as well and I don't need to mess with a K4 or other EQ's. The magnetic character of the ES remains, but is greatly reduced.... however, if you're a UST kind of guy or gal, you may not like it. I find that on any given night I can take it to an open mic night and simply plug and play and have the best guitar sound of the night. I like my Aura equipped guitars too, but on a step right up and play situation with no sound check, it is hard to beat the pure simplicity of the newest ES for good useable tone with no muss, no fuss!
Maybe this deserves its own thread, but is it worth the price for the upgrade. Is the 2010 that much better?