I'm working on software to automaticly update my control panel, it connects to the "Update Server" (forever to come up with that name), grabs a list of files and their last modified date, compares with the local files and then downloads any files that are new/updated.

I got this all working great. Creating, updating, deleting files and I even added a feature that checks if you modified a file on your own, and if you have, instead of replacing the file with all your great new mods with the latest version it simply creates a new file as filename.new (and you can continue using the old file with your mods until you add them to the new version).

But... I feel like I'm missing a bunch of important or nifty features, any ideas? What worries would you have with software doing the upgrade for you?