Available in an unaltered format and for a magnitude of other custom ROMS, the leaked update is arriving earlier than the expected official one, which is gearing for a roll-out sometime around or after June 15th. Specifically, it’s going to provide improved signal strength, carry along a handy 3G/4G toggle setting, and should resolve those pesky random reboot issues plaguing some handset owners. Even though you can download the leaked update right now, it’s still not certain whether or not it is going to be the actual final MR2 release build.
Nevertheless, if you seemingly can’t stand another moment experiencing issues with the ThunderBolt, you can always jump the gun and hope that this leaked update will correct all of your woes. If not, you'll just need to just wait some time until the official one arrives.
source: Android Police via Android Central