I just had a fight with an installation of Sharepoint and it dawned on my what I don’t like about Windows Installer. It is a black box. You click on the file and press next, next, next and magic happens. Personally, I would like to know where files are being put, which registry hives are being touched, are services being installed, are accounts being created. Did something go in the GAC, was a COM DLL registered.
It should be easy to add some kind of UI that summarizes what parts of the system were touched by the install. It would make me feel much more comfortable about installing stuff.