It really works beautifully. One of our applications coming up needs to work offline, and we found that because of the naming we were using, appcache was almost completely work-free to implement.

If the appcache.manifest changes, it rechecks all files (or in my case, would only pointpessly re-check those which haven't changed, and download new ones), and the appcache.manifest will change the second a single byte anywhere in the program changes.

It's fantastic.