Its technically not a new firmware because there are no enhancements. But it change the look of the player. You get a new user interface like the iphone style. You get a new opening and closing animation etc.
See the picture to see what the new interface looks like.
Warning it will only work on the player that look similar to the one in the picture.
For others who want to change their mp4 player firmware here is are some software you will need.
its a dos program just extract it and click extract.bat and let it run and when asked give the driver letter of your mp4 player. and it will download a file called dump.bin which is your mp4 players firmware.