I am a happy micro 4/3's user. I was one of the earliest adopters, buying a Panasonic GF1 when it was released, loved the 20mm pancake, and was blown away by the quality of the 14-45mm zoom. Truly, after dealing with APS-C and full format lenses, the super-tiny lenses were a revelation of usability. I was though, and remain, less-impressed with the camera's sensor. It's noisy as hell.
It's here that 4/3's desperately needed to advance. They left the gate already a generation behind everyone else on the market, and instead of at least staying there, they've fallen behind. Both Panasonic and Olympus continue to release camera after camera after fucking camera with no advancement. No development. It's infuriating.
The reason it's so damned annoying is because the lenses of m4/3's are just so great! The optics of a smaller sensor allow super-small lenses. As Leica users know, and as Fuji has shown with the X100, larger sensors can have small lenses, but not if you want a zoom lens. The 14-45mm lens from Panasonic would be twice the size, easily, on any larger formats.
For me, the m4/3's format all but obviated APS-C cameras because of the lens advantages, and while the quality is not up to APS-C snuff, and never will be, if you care about quality that much, and are already willing to accept weight and cost, stop pussyfooting and buy a full-format camera. Truly, m4/3's was like the same rebirth of enthusiasm that I had for photography after I bought my first EOS 20D and suddenly no longer had to worry about film. It felt like the future of an entire section of the market.
But, no. Instead, we have the only truly disruptive force in the imaging world fucking around. Poor marketing, poor design, and poor ideas. I'm sticking with m4/3's. No doubt about that. The advantage of the lens size is just too big to ignore. But with the way that Olympus and Panasonic are completely shooting themselves in the foot means that if Fuji does something with its new X100 format, or if Sony stops making total crap for its E-Series cameras, I'll jump ship faster than the GF1's shutter.