I have the G10 and love it for a little camera. Stays in my Mule, has taken a few knocks, nothing wrong with it, very well built. Great camera for taking creative shots, or for when you don't want to take your dSLR.
17mm f2.8 is pretty good, can take some nice action shots in the woods! Well you can, once you work out the delay on pressing the button.
Viewfinder isn't too bad, nowhere near the quality of a dSLR viewfinder, but not totally useless either.
Screen is excellent, build is excellent, optics are very good, don't think I would change it for another similar camera, apart from the G11.