M. Zuiko 12mm F2
Photo taken with E-P1 and Leica DG Summilux 25mm F1.4
So after 1 week of having the E-P1 with me everyday I would like to share my thoughts. It makes a big difference when I'm carrying light weight gear. Even if I'm carrying all 3 lenses (12, 25 and 45) it feels like it's not even there. I don't feel any stress in my wrists even after using it for a while. That is the biggest difference for me. I like it very much and I'm enjoying every second shooting with it. There's no doubt the Canon 5D Mark II has better image quality than the E-P1 but if you can compromise, I believe the E-P1 is the best in its class before the next generation PENs were released. Even Ken Rockwell has a review of the E-P1 and according to him it has the technical image quality of a DSLR or better, it's just not good enough for sports and action which I don't shoot.
I must say that I'm not trying to convince people to switch. My intention is to share my experiences so that it may help others in case they find themselves in the same boat as me or perhaps some are just looking for a second system. If I have the money, I will say it again, I will still have my 5D Mark II with me or maybe even upgrade to the 5D Mark III. For what I do and my style of shooting I find that a m4/3 system is enough and has satisfied my likes up to 90-95% of the time.