So much this. I was interested in using WiX, but it's just impenetrable for a noob, and any "beginners" guides were either hugely out of date or just assumed you understood what GUID you should be using and if it was important or not to change the example they gave. Quickly gave up. :(
I made the huge mistake of believing that the community would help with documentation. I knew working with the internals of the Windows Installer would be challenging for most developers, but I really thought they'd help share what they learned and contribute to the documentation. Almost no one did. So, I've picked it up as a task we're doing at FireGiant... but there is a lot to do and it will take time.