Thanks to our friends at Olympus, I was fortunate enough to get to take a prototype OM-D E-M5 on my recent vacation to San Francisco. I wanted to travel light while still having all the quality and control of my full-size SLR and, having handled an E-M5 previously, I knew this was going to be a great choice. 
I packed up the camera and three lenses: my 14-150mm, 9-18mm, and the 45mm f/1.8 from our rental department. The whole package was still very compact, despite providing the equivalent coverage from 18mm to 300mm, along with the 45mm f/1.8 for very low light situations. (For this trip I didn’t take the optional battery grip to save space, though I find it really adds to the handling of the camera.)
I'm happy to report that Olympus has really done a great job with this new system. The E-M5 handles well and delivers excellent photos. A few stand-out features really impressed me:

Art Filter Bracketing lets you apply multiple filters to a single photo to automatically create several different versions
The only drawback I found was that two of the buttons on the back are rather small, and can be difficult to hit. With a little practice I got better at it, but if you have large hands it could still be a bit frustrating.
Photo Album: See more of Mike's E-M5 pictures from San Fancisco
I’ve owned a lot of cameras over the years: film SLRs from a Minolta X-700 to Nikon FE2 and FM2, a Bronica SQ-A medium format outfit, a Nikon D70, and currently an Olympus E5. I’ve also used almost every DSLR from our rental department. They’ve been my cameras for serious picture taking, giving me complete control and high quality images. Of course I’ve had several compact point-and-shoot cameras too. Pocket-sized and with decent image quality, these are my “fun” cameras.
Recently, the Olympus PEN cameras have been a big go-to for me. They’re smaller than a DSLR, but with more control and better image quality than a point-and-shoot. The Art Filters save time by providing creative options right in the camera. All in all, it’s a compelling feature set. The few areas I found lacking have been difficulty adjusting settings, slow focusing, and problems with low light. I have an older E-PL2, and the current generation of PEN cameras now focus much faster and perform better in low light. But I didn’t upgrade, hoping to see something a little different come to market. And then a couple months ago Olympus announced the E-M5, the first camera in the new OM-D family.
For me, the OM-D E-M5 is a perfect choice for my main camera. Small, like the PEN, but with ready access to all the options I want, reminding me of my old FE2. With those quick adjustments I can get the image I see in my mind’s eye. With weather-sealing and a very functional vertical grip, it’s now a compact replacement for my full-size “serious” cameras. I won’t drone on about the new technology inside the camera. I will say it all comes together perfectly. Quality-wise, the images are superb. Improved low light performance, improved stabilization, super-fast autofocus… it all helped me bring back exactly the photos I wanted.
The OM-D is a logical evolution of the digital camera, and performs admirably. This style of camera, what many call a Compact System Camera (CSC), will appeal to a lot of people. If you’re looking for more control and higher quality than a point and shoot, but don’t want to give up the compact size so you can easily take the camera with you, give this type of camera a serious look. While the PEN series was one of the first CSCs, Olympus, Sony and now Nikon have added a bunch of models to choose from. With CSCs offering such a vast array of features, you’ll likely find a great match for your needs.