Upgraded my home installation this weekend and ran into two issues:
1. SP1 doesn't allow you to set the external FQDN name of the Default receive connector to something that is not the real server FQDN or NETBIOS name. This is because the receive connector has the "Exchange Servers" authentication method set. If you are running without an Edge server and using the Hub Transport as the external gateway, you need to set the external FQDN to your external host name. In the documentation, Microsoft advises not to change the FQDN of the Default Receive connector, because it will give problems when Hub Transport servers want to communicate with each other. Since my setup only has one Hub Transport server, I decided to leave the external FQDN set and turn off the "Exchange Servers" authentication option. This allowed me to install SP1 and mail flow is still working. FYI my mailbox server role is on the same server as the hub transport server.
2. If you have any UM language packs other than US English installed, the SP1 install will not run and tells you to uninstall the additional language packs. After doing this, SP1 will install, but you will not be able to reinstall the language packs again. The error message you get is: A Unified Messaging Language Pack is already installed for the culture 'nl-NL' (for example). I discovered that you need to delete the appropriate registry value for the language packs that you uninstalled from: HKEY_LOCAL_MACHINESOFTWAREMicrosoftExchangev8.0UnifiedMessagingRoleLanguagePacks. After deleting they key, the language pack would install again.