I know tekkub will hate me but reading this forum a lot, I think this could be an interesting topic and I will start by a first suggestions.
This application is very important for most of us so first "thank" to the creator.
At the end of update, display the result of all changelog.txt
Checking changelog.txt files for all addOns is time consuming and I am more than sure that only a few people do it, so this will help people to focus on testing ALL changes, help them to know what have been change and what action to take (for example Huge Text Box Problem).
Automatic backup : zip the current addOn's folder before update it.
This way I will never spam tekkub with stupid posts as I did ;) and it will be very easy to restore the previous version. And why not an option "Restore previous used version" on the popup menu.
This is just a suggestion and if you think this topic has no reason to exist, please just delete it.
I actualy like this idea alot. One of the main reasons I use an SVN client is I can read the log immediatly after update without drilling down into a folder to find a text file.
Id also like to 2nd the idea of running a backup prior to downloading updates, but Id want it to include the WTF Dir because sometimes a fubar update can mess up the saved variables. I run a backup of my interface / wtf folders before every update just to make sure I got a rollback if stuff goes FUBAR.
If those two features were in, I am almost positive id start using the updater rather than an SVN client.