I've been using Duet for some time now. Pros: - Simple to use. Install the drivers on Mac, run the program on your iPad, and go. - Acts like any another mon

I've been using Duet for some time now. Pros: - Simple to use. Install the drivers on Mac, run the program on your iPad, and go. - Acts like any another monitor. You can adjust orientation with other monitors and resolution. Different choices in performance. Adjust vertical orientation on iPad and screen just updates. - Very responsive, if not always very performant. No lag or jitter in image/sound, but graphics performance can be slower (lower FPS). You can play video games on it, but I wouldn't do it for a living. - Sometimes you just want to sit down in a coffee shop and have a second monitor handy. This does that. - Touch screen triggers mouse input, if that's useful for you. Cons: - Your CPU is doing all the graphic card duty. On my i7 at retina resolution, you'll chew 50% of a core. This will eat battery and your machine will run warm. But not hot, like a video game. - Odd graphic issues when you also have a secondary monitor plugged in through HTML. Works just fine, in general, but sometimes it will loose track of what to refresh or update on the monitors. Disconnecting and reconnecting always clears this up. Most often happens when I lock the computer. - Sometimes, it just gets confused about connecting. Again, stop and restart the app on iPad fixes it. It's not perfect, but it works well enough that I certainly don't regret getting it.