I've been beta testing duet for about a month now. As a person that travels a lot, it's awesome. The developers have done an incredible job, and have been very responsive in fixing the bugs I've reported to them.<p>However, a couple of things to note. Firstly, this is lag free, but still not something you should play videos on. I'm not sure what the framerate is, but I'd be surprised if it's over 30fps. I believe this is probably a result of using USB.<p>Secondly, I never thought I'd say this, but retina is not your friend. On the new iPads, the OS X menu bar is <i>maybe</i> a centimeter tall. Obviously, you can change the resolution, but I like hi-res, and you just see so little when you bump it up (keep in mind the new iPad is only 1024 by 768).<p>The app is the best it can be, but what I'd emphasize is that most people should really get a second monitor, if that's what they're looking for. I understand you could save some money, but iPads just don't offer enough real estate.<p>Again, kudos to the devs for doing a great job on the app though.