In support of Giuliano's frustration: we're about to roll out Confluence 3.0 here, but the RTE is still too funky (especially in regards to rendering vertical white space (blank lines) consistently) that I'm afraid to enable it for fear of turning off new users. Note that our previous Wiki (MediaWiki) eventually withered away as many of our users (e.g., artists, who are tuned in to style and presentation) simply couldn't stand/use wiki markup. In this case, the absense of a functioning WYSIWYG editor finally killed the wiki.
These users are already apprehensive about the new wiki they've heard about. My current thinkng is to not show the RTE at all, and rely on Connector. I've made some simple keystroke macros in Word 2007 to format a doc (via Connector) to more closely match what they actually see on the wiki, and am presently working on CSS and themes on the wiki side to make a closer match as well.
So, my experience has been, more than anything else, lack of a reasonable editor can kill a wiki.
i know it's a tough job to implement a decent RTE, but, to us, it's critical. My two cents.