I have one and have shot a couple thousand photos with it so far. I have the silver one with the 14-42 kit lens and also use adapted M and LTM lenses on it. Auto focus with the kit lens is pretty poor, worse even then my 10 year old sony point and shoot. The AF is slow, and consistently misses completely with nothing in focus, when you try and lock on something moving, say in street shooting, it is completely outclassed by every other auto focus camera I have ever used. I hear things are better with panasonic lenses but I dont have any on hand to try and I hope Olympus is working on a updated AF software patch for the camera because im shocked they would release it with such crappy AF performance. Using adapted lenses is kind of hit and miss too, while it is possible to focus using the magnified focus thing it is cumbersome and ill conceived. Also it is very possible to take great care manually focusing something, snap the picture and its still not in focus. I have yet to stick the camera on a tripod and really dig into the manual focusing in a controlled environment though.
Needless to say the GRD's snap mode is significantly easier to use all around.
Also I dont care for the "HELLO I'M ON!!!" light around the on/off button.
Oh...also Adobe does not support Olympus's .ORF raw files yet in CameraRAW which is a real pain in the neck.
But not all is bad. Image quality is good for a camera this size, and while I dont think it stands up to my gf's Canon 5D it does have a lot going for it. Also its a very sturdy feeling thing for being so small. The screen though lacking resolution is pretty easy to use outdoors and keeps up with what is in front of the camera. High ISO shots are good and much better then the GRD. I also like having image stabilization on all the lenses I use on the camera. The kit lens is pretty smart for what it is all except the rotating front element which I keep banging on windows and stuff. The shutter sound is quiet enough to use in many places where you want to be a little more discreet and the AF motor does not buzz or hum. Being able to shoot adapted lenses on the camera and still be able to get some of the feeling from those lenses is great, photos I take with my Zeiss lenses have that "zeissness" to them that I didnt see with the panasonic g1 when I owned one for a short time. While that "zeissness" is not as apparent as it is with film, its progress for digital as far as im concerned.
My suggestion to you as someone who came off a GRD as well....wait for Panasonic's upcoming GF1 and see what is said about that before you rush off to buy. The new panasonic sure lacks the Olympus's charming looks though.