Apple TV with Airplay in theory is awesome for presentations. I've setup Apple TV on a bunch of LED screens for a client, with the intention of using Airplay for displaying presentations from Macbooks. So far, the solution has been close to useless. The lag is unbearable, even for simply actions like changing webpages and PPT pages. In the end, users end up going back to HDMI or even Thunderbolt to DVI/VGA connectors for presentations. To make it worse, it seems that different versions of OS X will give a variety of glitchy behavior on Airplay.