I've used it on American (and possibly Delta?) and really thought that it was transformational. I don't have a particularly challenging job at the moment, but it was still great to be able to push through an email backlog in otherwise dead time.

I found it surprisingly fast and responsive as well, though you still tend to notice that you're 35,000 feet up.

PS I initially misread the thread as "Wife on board - how is it?", which is why I actually clicked on it..