1. It will make your phone look like it is built for a little kid that never seen a phone before.
It looks cheap and it is much harder to read
2. It will now check the charger that you use, if it not Apple it won't let the phone charge.
Never mind that I have been using this charger and cable since I got the phone, it doesn't work now.
3. Like with other updates, it changes a lot of default settings. If you care about privacy and security you will need to back through many setting screens and make sure that things are set the way that you want them.
These guys make the NSA look like rookies.