I don't know what VW has done to improve the Golf/Jetta but if the what is under the skin has been changed to the same degree as the outter skin, which is to say not much, then I have no interest in this car.
The styling of the Golf has been gradually updated in the past decade or so, much of the shape of the car, dimensions, layout, etc, is retained. Newer Golf gets crystal-clear lights, smoother body panel lines, etc. This strategy may have kept the car looking up-to-date on the outside, but sitting in and driving the Golf/Jetta reminds you of a 10 year old car. All engines, including the VR6, serves up a healthy serving of noise and vibration, which is exacerbated by chassis and isolation materials that appear to do very little in subduing the racket. The suspension may handle well after being touched my aftermarket hands, but stock it provides neither confidence nor comfort. Miles of black-on-black trim on the inside places the mood somewhere between somber and morose. Switch gears are mushy to push, dials are gritty to turn, and someone, for the love of humanly detectable spectrum wavelengths, change that purple cluster illumination. These days, comments about VWs having a nice interior is just a knee jerk reaction - it might have been true 10 years ago, but the rest of the world has moved forward.
In short, driving in a Golf/Jetta of any trim provides the feel of a heavy small car that feels nervous, unsubstantial, and cheap. Looking at the sticker brings to mind a host of better executed automotive designs that you could have instead.
The above is the impression my wife and I got after test driving a host of VW cars during our car shopping. And with this new VW, the styling is again very evolutionary. I don't think the average person would be able to tell that this is a new Golf from the rear or side. The front treatment looks positively weird, like the current Passat. Different is only better if it is actually better.
I'll test-drive the car when it comes out, but as it stands, the Mazda3 is a far more refined vehicle with a more premium feel (thought I'd never say this about a Mazda). Is the new Golf a big improvement on the old one? I am not holding my breath.