The only good thing about rooting is you get superadmin mode. So if you ever have any programs running in the background and you want to stop them permantely, you can freeze them (only done by rooting). Thats the only good thing I found.
A little close minded. Without a custom rom or super user rights from root you can't bluetooth dial from a secure locked screen with any Samsung phone. However if you make the smart choice an go with another brand instead of wasting 699 on what is considered "top" of the line phone you will have a better user experience. The galaxy s3 lacks so many features found on HTC, Motorola and LG phones that without hacking the phone you wouldn't be able to achieve said basic features.
That being said, it takes an especially stupid person to brick your phone from flashing. Most flashing errors can simply be restored. Most of this is done by phone companies because of all the useless bundled software that comes with it preys on stupid people to buy more services from them.
People are really in the dark about what rooting is and custom roms.