My initial attention was possessed by this camera body's size. At the time I got to know of the E-PM1, I wasn't exactly searching for a new camera. I own a compact Canon Powershot and an iPhone 4. Over time I had lost my passion for photography and thus had become lazy to carry my compact unit with me unless there was a significant reason to do so. I had vowed never to own a DSLR as I knew that if I did, it wouldn't be long before I became lazy to carry all that gear around with me wherever I went. When I started looking into the specifications, test photos, reviews of the E-PM1 it became apparent to me that it is possible to have such a compact camera that beats much larger DSLR systems. I learned that this mirrorless camera had the same sensor size as all of its larger Four Third mount cameras and that this body is compatible with the full range of micro Four Third and full size Four Third lenses. These facts were what impressed me the most because I then realised that I could be walking around with a stealthy camera body that's slimmer and smaller than many compact cameras in the market, yet have the capabilities to beat the older Four Third DSLR bodies.
One of the important decision criteria was the ability to carry a camera around without a bag that had to be opened to gain access. I searched online and found that there were some camera cases from China that fit this unit perfectly and some even had a bump on the top to accommodate the accompanying Flash unit. The discovery of these imitation leather cases provided the solution that I was looking for. I was then able to carry the E-PM1 around, hung from my neck with a case that can be easily unbuttoned, folded back, and closed again after the camera had been used. Although there are other mirrorless cameras on the market that have larger sensor sizes, they also necessitate using a larger lens and thus increase the bulk of the entire package. This criticism of the micro Four Third form factor was a compromise that I was willing to make due to the mobility and stealthiness that the Olympus E-PM1 offers.
I'm pleased to say that this has been one of the best purchases that I've made.