Despite the price and weight this is an excellent and worthwhile camera which along with the unbeatable Zuiko lenses makes a really good system for a practical photographer. Outstanding image quality up to ISO 800, good IQ at 1600 at 50% crop factor and usable images up to (just about) ISO 6400 if you expose to the right and do a little work in post on noise reduction.
Excellent dust-busting in Oly cameras means that in three years of using other Oly DSLRs I have never had to clean a sensor. Very good in-camera image stabilisation for any lens mounted gives you good low-light ability especially with the pro and top grade lenses. With those lenses the system is high-performing, very weatherproof, cold-proof, robust and reliable. Battery life is good. Olympus has improved the autofocusing performance, fastest in class, by extending its performance in low light unassisted. Sweet to hold and good to operate, with extensive customisation options. The out of camera jpegs are outstandingly good for speed and convenience, and if you shoot RAW then with Zuiko lenses you will have excellent detail and pretty much edge-to-edge sharpness even at widest apertures. I haven't used the HD video capability.
While a few other manufacturers' products may beat any one of Olympus' characteristics by a short head, the overall system is up with the best or better.
I'm not an Olympus fanboy but was critical of my last, lesser, Olympus DSLR. This one, however, is the goods and I very much doubt it will be the last four-thirds camera unless they can beat its all-round spec (including fast focusing) with micro four-thirds.