I bought a GF1, 20mm F1.7, 14-45mm, and 7-14mm shortly after they came out. I've found it to be a great portable camera system. The 20mm F1.7 is great for taking social shots. The greater depth of field from the smaller sensor makes F1.7 a lot easier to use than it would be on a full-frame camera. The autofocus is accurate, and pretty fast. The face detection is a very useful feature - just compose the shot and focus, regardless of where the face is in the shot. With my 5D II I have to choose the right focus point and position it over the face, which slows things down.
On the other hand, the image quality isn't in the same league as a full-frame DSLR (you can't beat physics), and the autofocus system is pretty useless for tracking moving targets. This limits the camera's usefulness for photographing young children, since they seldom stay still for long.