Several of my long used 3rd party productivity apps are less stable on iOS 6.01/iPhone 5 than they were on iOS 5/iPhone 4S. I've note seen this mentioned elsewhere, so perhaps it's a coincidental problem in several of the apps I use.
The apps are still usable, it's primarily an annoyance. I'm restarting the phone more frequently to see if that helps.
Sharing for what it's worth. I also asked on app.net.