I normally shoot with a full sized DSLR, for both personal and professional work, but often find myself failing to grab my camera for casual shooting due to the bulk and weight.
In addition, my wife and I love to camp and hike, and at my age carrying 40-50 lbs. of camera gear has become quite restrictive. I decided to invest in the "Micro Four Thirds" System based on the size and image quality the system offers.
The Olympus E-PL2 is an amazingly good camera with great image quality, excellent lenses, an abundance of features -- and on top of those benefits it is extremely compact and light weight. A minor shortcoming is the lack of a built in electronic viewfinder (EVF). If a person is used to shooting with an eye level finder, like I am, it is worth investing in the excellent VF-2 or VF-3 accessory EVF offered by Olympus (albeit at an additional $180-$200). I love the finder which simply slips on the the camera hotshoe and plugs into an accessory port just below the hotshoe. The images produced by this very small camera rival the image quality of my professional cameras. It focuses fast and accurately, has excellent high ISO performance up to 3200 (it goes up to ISO 6400), and offers fun features such aa a variety of built in "Art" filters.
Have I mentioned that it's light? I have a small Lowepro camera bag that contains the E-PL2, 14-42mm (28-84mm equivalent) lens, 40-150mm (80-300mm equiv.)lens, 45mm f1.8(90mm equiv.)
lens, 4/3's lens converter (for using my DSLR lenses), Wcon-P01 wide converter, spare batteries, etc. and I can literally lift the full bag with my little finger!
I love it!