As always, it’s a personal call.
Both myself and a friend updated it again, and while we did and still do have issues after the update, I couldn’t say they were caused by it vs just general bugs in ios15.
One bug in my case: I tried having 2 cell numbers from 2 different carriers about a year ago (physical SIM + eSIM) to check if Verizon was truly superior to AT&T (I’ve had AT&T all my life due to its reliability EVERYWHERE), but, I had been having data connectivity issues with AT&T, which in retrospect, I now realize they were all iPhone-caused issues by apple’s buggy iOS and REALLY BAD cell modems (huge difference in cell modem quality in iPhone 13 vs 12, OMG - and I’ve had several iPhone 12 Pro Max, so can’t blame just one phone as defective) - anywho, I digress - I found a couple of weeks later that Verizon was way worse (I live in Miami & some places had ZERO reception - never experienced that w AT&T) so I cancelled the Verizon line.
All this backdrop was to say that after the second update to iOS 15 on 13 Pro Max, whenever I attempted called some of my favorites/fam, for which I had specified to default carrier of the 2 lines from a year ago, and when I called them, system gave me an error saying that THE DEFAULT LINE WAS NO LONGER AVAILABLE.
Really? LOL. So all of the sudden I had to go into each of their A/B contacts and remove the default line assignment, which was not something that was visible after I removed the second line a year ago. Now, I also put my Contacts to sync to iCloud a couple of weeks ago, so that in itself deleted all custom text and call tones I had assigned to everyone and could have caused this too.
As far as my friend, his phone started rejecting to connect to Apple CarPlay wirelessly, and subsequently via Bluetooth as well. But I’ve had that issue with all iPhones in my car every so many days of use.
Again, I can’t say this is due to having upgraded to 15.0 twice vs just the usual ‘bug city’ nature of iOS.