Its meant to fix the reboot issue some people are having (I have 2, had one replaced so 3 all together, and have had the problem with neither. One of my phones is on the update and one hasnt been updated, Since I and some other havent had the problems, these are they 2 only things I honest see with that the update did:
One being the phone boots up ALOT quicker
And it blocks root and is unrootable at the moment.
Those are the only 2 things I see it did, but then again I didnt,dont have and havent had any issues, so with no issues I cant tell you if it fixed anything other user are having problems with.