Too many false positives and other issues Rated 3 out of 5 stars
I tested the current version and the beta version from the author's homepage.
Both versions notify about updated pages but most times there are no (visible) changes - nothing gets highlighted. Thus you are unable to exclude those unimportant areas.
The UpdateScanner feature "Ignore changes of less than xx characters" would be helpful here but unfortunately is missing.
SiteDelta still lacks of a "Mark changes as seen for all pages" - button.
If you open a updated page on notification you still need to choose 'Highlight changes' from the status-bar menu what is annoying. Sure, the addon provides an option called 'Highlight changes on page visit' which always works, but sometimes you might want to visit the page without highlighting which is impossible without opening the addon options again.
I tested notification sounds 'Beep' and 'System alert' on a Windows XP machine, both failed with SiteDelta, but are working for other applications. No errors logged in js-console.
SiteDelta promises a lot of nice features (especially the include/exclude region options, however I was unable to test them all), but the basic functions still need some work. Until then I am going back to the UpdateScanner addon which currently works best for me.
To the developer: Viel Erfolg!
If you compare this addon with the UpdateScanner addon you should have one of both disabled!!
Otherwise you get a 'Unresponsive script warning' (SiteDeltaService.js:1040) as soon as you choose 'ShowChangesInNewTab' from UpdateScanner. Most likely caused by UpdateScanner's very large data: URL's which are known to cause such issues.