Some compatibility issues can be observed when using Office 2010 with Sharepoint 2007
1)Word documents open in read mode when selecting the document link in sharepoint (not using dropdown menu). The behavior in Office 2007 was documents would open in edit mode.
To open word docs in edit mode using office 2010 and SharePoint 2007 one needs to use the dropdown menu
2) Excel files, when selecting the document link (not the dropdown menu), are requiring a refresh before changes can be saved. Any merges of data are lost during the refresh. The refresh error/warning is a compat issue between office 2010 and SharePoint 2007.