First, let me say this plugin is great! I recently moved from a free domain to http://akted.com, and all links to my old domain appear to have been changed correctly. However, I do have one concern. According to http://codex.wordpress.org/Changing_The_Site_URL#Important_GUID_Note, you should never change the GUID since that is how feed readers know whether or not a particular post/page has been served up yet. From the aforementioned page:
It is critical that you do NOT change the contents of this field.
Never, ever, change the contents of the GUID column, under any circumstances.
One exception is attachment media: