[astrodust]

The idea is they come basically for free with your processor, bundled in, with the additional advantage of not requiring more space for a separate graphics unit and additional GPU memory plus associated cooling.

For some applications this is an enormous benefit. For an office computer, which doesn't require high-end 3D to start with, the HD4000 will be more than good enough.

They're meant for gaming, but not performance gaming. You can play something like Starcraft 2 on it without much trouble if you tune it down to "Low" settings. It just doesn't look anywhere near as amazing as it would on "Ultra".