I did an OTA installation on my iP11, and it seemed to go fine, not noticed any significant performance issues so far.
Oh, apart from the only Widget I bothered setting up, which was the clock. Which was showing completely the wrong time, for no reason I could see. I only have one world clock set, which is London, so it could have randomly selected another time zone, but nothing I could find would set it back to London time, so I removed the Widget and it’s back to the correct time.
Hopefully there will be some more widgets for the likes of WeatherProHD and Shazam, and Dark Sky will make its presence felt in the native weather app.