According to TaylorMade, the M2 is not a replacement for the M1. It is part of the same family.
From above it looks identical to the M1 - which is a good thing. The M1 is the best looking driver that TaylorMade have produced for a very long time. The M stands for Multi-Material and the carbon composite crown gives these drivers a fabulous, business-like appearance. That crown is ultra-thin, ultra-lite and weight for weight it is stronger than any known metal.
The main difference between the M1 and the M2 is that the M2 lacks the slider mechanisms of the M1, and is therefore less adjustable. You can change the loft and lie on an M2, but that's as far as it goes. On the plus side, the M2 is lighter, and less expensive.
Click the picture (right) to watch a video review of the TaylorMade M2 Driver.