Lots of information out there
Since you have to wait until October to actually buy one, at least you can kill some time reading about it.
Overall, the EOS M, with its slim form factor and large image sensor, would likely appeal to compact upgraders looking for dSLR-like quality minus the bulk as well as dSLR, users who have already invested in a stable of Canon glass.
From Digital Camera Info
The EOS M is a camera for the masses, a simple-to-use interchangeable lens camera that won’t intimidate, but doesn’t skimp on the components or build quality. Its similarity to the Canon T4i is going to make for some tough buying decisions for many people in the sub-$1000 camera market; for just $799.99 this October, you can likely get all of the T4i’s performance in a smaller package.