Is it a good idea to upgrade my iPhone OS to iOS 6.1?

The Choice to Update or not is yours to make.

http://support.apple.com/kb/DL1624

Just make a full day appointment on Aprl 1st. Save it and then try to open iCal after March.

It will not work.

Just to give you an exemple of a bug on 6.0.1 repaired with 6.1

Good point Walter 😎

Thanks AnaMusic... to be honest it was the only bug I found in 6.0.1 but really bitter becaese we have Easter Monday in April 1st and it is loaded in the Holyday Cal as full day.