We upgraded immediately using the "WordPress Database Backup" plugin and then the "InstantUpgrade" plugin. I haven't noticed any problems so far. Of course, different sites use different combinations of plugins. I hope this info helps people. The plugins we are using on our Church site are listed at "WordPress Plugins In Use." The list links to the plugin sites.
Land & Building Fund Donations
Less Applicable Transaction Fees
reflects cleared transactions
& donations before expenses
to the Christian Commons Project™