I just got my Twiddler about a month ago and it works just fine with my iPad mini. It had no problem pairing as a bluetooth device. I've only used it as a keyboard input though - typing into Notes, search engines, typing.com (for practice!), etc.
I haven't really played with trying to open apps or using it for other navigational purposes. iPads don't natively have cursors or "focus" (at least not that I'm aware of), so I didn't even think to try and use it that way. I doubt even alt-tab would work. I could give it a shot this weekend. If someone's figured out "normal" wireless keyboard navigation for iPads, it's bound to work with the Twiddler.
And it sounds like Alex hasn't had any problems mapping the Cmd key.