Did a direct transfer from 13 Pro to 14 Pro, so far absolutely no issues with the OS.
The direct transfer process, at least if you have a lot of stuff, does seem to be a little… not seamless feeling, I guess? There are times when it pauses for a little while, but there is no activity indicator, so it feels like it either didn’t accept your last input or is hung. Having at least a spinner, but better yet some kind of pseudo-progress bar at the top of the screen, would make the whole thing feel better even if it made no difference in speed. That’s not new, though, I’ve noticed something similar since I started doing direct transfers a while ago.
I was impressed with the physical SIM to eSIM transfer, though—just tapped yes and waited a minute. Was so smooth I made my SO’s SIM an eSIM when moving them to my old phone even though it wasn’t necessary yet.
Interestingly the only thing that didn’t work flawlessly when moving to a new phone was a few 3rd party apps that seemed to have cached bad authentication data and wouldn’t log in or gave vague and wrong error messages about the network being down.