There are a few notable (mostly optional) improvements for 2015, such as an optional Forward Collision Warning System, optional Blind Spot Monitor w/ Rear Traffic Assist and optional Bi-Xenon Headlights.
The clean interior and exterior design looks very similar to the 2014 Jetta, with really only minor cosmetic changes to the appearance of the headlights, front cowl and a minor taillight tweak.
Diesel lovers should take note that the 2015 TDi Jetta has improved mpg figures to show 46 highway mpg and now also has standard "Active grille shutters for aero efficiency". Sounds like technology shared from VW's prestigious makes such as Bugatti or Lamborghini. The power is up 10 horsepower, to a Passat like 150hp. The improvement in fuel mileage and the slight, 10 horsepower bump comes at some cost in exclusivity and independence however. The 2015 horsepower bump and fuel mpg gains will now be achieved in much the same way all other diesels currently on the US market handle their exhaust emissions and is now no longer Urea tank free.
When I heard the news that a urea tank was now a new thing in the 2015 diesel Jettas I was hit with a brief bit of nausea. My experience with the diesel Chevy Cruz came to the front of my mind and how the already small trunk was made even smaller by the urea tank.
After talking with Volkswagen I was assured that the trunk volume had not been compromised. They said it even increased .1 cubic foot from last year's model. The tank was mounted where it won't impact passenger or luggage capacity. The urea fill tank will be mounted conveniently next to the diesel fuel fill, under the fuel lid.
In conclusion, overall the safety improvements sound promising, although I am still not crazy about the addition of the urea tank. If I was in the market soon for a new car I might put my order in for the all new 2015 Golf TDi Sportswagen, (currently known as the Jetta Sportswagen) or lease a TDi sedan now if I couldn't wait.