Required reading for anyone wanting lots of details and macro pictures of Push.
In summary:
But the Launchpad and APC40 now feel more like experiments in comparison to Push. The new, sleek black controller is the most complete hardware Ableton has ever released, the first to properly carry the Ableton name. In look, feel, and function, it really seems the first time Ableton has expressed their vision of hardware the way Live originally did for software.