I posted this in another thread, but it might be interesting in it's own thread:
It IS a problem, but NOT every Thunderbolt has this issue. Mine did. It was 100% stock, not rooted or anything. After the update, it started rebooting on its own. I tried the remove battery trick, didn't help. Removed new applications since the update, didn't help. Did the factory data reset....and it's been perfect since relative to reboots.
I do still get the phone showing 4G service but no data connect, and no fall back to 3G until I get out of the 4G area. I may have found a fix for that too... Hasn't been long enought to really test this out...but using the suggested ##778 (EPST edit mode) and I set the Preferred Mode to CDMA HDR and the Preferred Mode (9k) to HDR LTE mode. Prefered had been at CDMA and preferred 9K had been at LTE only.
For the rest of yesterday....that seem to help A LOT. But once I left work, I'm out of the 4G area, so hard to tell if it really helped or if it was just a quirk. 3G is fine, as it always has been.
As usual, your mileage may vary, don't forget to COMMIT the modfications and always...ALWAYS write down what the original settings are before you change anything!