The ability to very quickly put a few bits of information together and make them available to my entire organization is priceless, especially using a tool that easily allows my peers to contribute and evolve my initial work.
Grr, certain things drive me crazy with Confluence
Having to format a a table of contents the way I like it on every single new page I create (let me save my format please!)
Formatting a page en-masse seems not to be a feature (e.g. I want to divide a page into two new sections which would be Heading 1. In order to do this I must go through every other heading on the page and manually format the headings down one level. Heading 1s must be set to Heading 2s, All Heading 2s must be set to Heading 3s. All Heading 3s must be set to Heading 4s, etc.)
Cutting and pasting code onto a page? I always use the same settings with the Code Block macro. Please let me save these settings as a default so I don't have to re-select them every time. ).
Trying to migrate a large number of pages between spaces? Nightmare. I was left with many pages stuck in some sort of nether world where they showed in the old space but when trying to migrate them to a new space I received a message akin to message: "Page already exists in that space". <face palm>
Make a decision on how spaces will be used at the very begining. My recommendation? A single space for your entire company. There is no need to segregate the information into the silos that spaces create.
Does confluence frustrate me? Yes. Would I get rid of its wiki-like ability to provide information to my company in a quick low friction format? Never. (I just want less friction in a few key areas).