Thus far, it's worked pretty flawlessly. Any problems with setup have been my own. Getting the forums working took all of an hour. I plan on the same amount of time for the chat.
They've got pretty extensive support for FAQ's, but I decided that just making a locked forum item would be the easiest way to go about it. That way all the support stuff (forum and FAQ) is in one place.
Still playing with the templates. Replacing the generic top-banner with a Flash movie took a couple of tries, but it's working now. I'm still futzing with the tables, because the default template isn't quite smart enough to size the middle panel if there's nothing in the side panels. Click the "news" button for an example.
Biggest upcoming problem I see is with how I'll dip into the user database via Flash (for global high-score tables). Mambo has nice PHP-based objects to do that very thing, but the documentation for 'em is nonexistent. Once that's figured out, I think it'll be pretty straightforward to make global high-score tables and such that'll talk with the user-database.
I'll probably replace that "search" box up in the corner with another Flash applet that scrolls the latest high scores for the games.