So far b3 has been a big improvement over b2 for me. b2 was characterized by torching my phone. At times it would become too hot to hold. I frequently couldn't charge it as it was too hot and the phone would notify me that charging would continue when the temperature dropped. It had a deleterious impact on how I used the phone. I reported the issue. My battery health dropped from 99% to 91% over the course of two weeks.
Happily, I upgrade annually, so not stressed about the damage to my battery, but I was really hoping b3 was going to fix that issue. If it didn't, I would've been concerned that some combination of the software I had installed or the hardware on my phone were contributory and that my phone would be in this quasi-usable state until the new phones come out.
And, even in just the first few hours since installing b3 it's behaving just as well as it did before b2. Quite pleased.