Just picked up the GX1 last week. So far looks very promising, although not familiar with all the features as of yet.
I already have a Canon EOS 450D DSLR, but wanted a smaller, good quality camera which would be more portable. You cannot escape the maxim "the camera you use is the one you carry with you". So after much research and some excellent advice from a professional photographer who owns a GF1, I opted for the GX1. You will find the Sony NEX variants fair marginally better in reviews on several counts, but to be honest I fell for the styling and retro feel of the GX1. It covers all the bases adequately and feels / looks solid with its metal construction and tight dials. Would opt for the power zoom (PZ) kit lens which is approx £120 more expensive than the basic zoom package. Also, shop around as Amazon is way too expensive at time of writing (Feb 2012). You can pick up the PZ kit elsewhere for about £600, which is only £20 more than Amazon are selling the more basic package for.
The advantage of the PZ is it compacts to the size of a pancake lens, so it will truly fit in your pocket or a stylish body case, rather than a great big bag in order to fit the cheaper non collapsible zoom lens kit.
Also, up to end of March 2012, some online dealers are supporting the Panasonic offer for free Adobe Lightroom 3, which is approx £100 retail. So appears a no-brainer. Go spend your cash !