The GXR is equally fun and frustrating to use. I love the handling and build as well as the fantastic lens but the slow and unreliable AF manage to frustrate me to no end every time. I almost missed this picture because the camera mis-focused twice (and took ages to actually get there) and made a lot of noise so I had to manually focus in the end. This works great thanks to the distance and DOF scale but due to the useless magnification it's impossible to see if I focused properly so it's always a guesswork.
Overall, I enjoyed having the GXR with me but wished I would have taken the GF1 instead because it is simply more reliable to get the shot and has a working AF even in low light.