The auto mode is very impressive in terms of taking any situation and shooting a decent snap. It handles low light, high motion, shaky hands, etc. all very well. The images that come out of it seem to be generally quite grainy compared to the S90, but I think the difference is just that the main difference is that the Panasonic is not doing so much noise reduction in the firmware (obviously the sensor is smaller too). If you do some software noise reduction the images step up nicely.
One thing I didn't anticipate is how awesome the long optical zoom is. It does 12X optical zoom which is pretty amazing for an ultracompact. With the good auto-stabilization, it means you can just crank up far zooms and snap shots and get closeups I've never been able to shoot before. Very cool.
But the biggest win by far is the amazing HD video capability. It records 720p AVCHD in real time (AVCHD is just a limited profile of H264 in a different package; the MTS or M2TS files can be played directly by MPC or VLC). When I first saw that it had a dedicated button for start/stop video I thought "that's dumb, that should just be a scene mode" , but oh how wrong I was. Video is fucking *awesome* and it's sweet to just have it on a button so you can record video at any moment without mucking about with scene modes. We shot a few videos and they're just so much more fun and interesting than stills. In fact I can hardly bear to look at still any more, it's like a paradigm shift, I want video of everything now.
One annoyance is that neither MPC nor VLC have an option to play back video rotated 90. I don't want to decode and re-encode just to rotate 90, I want my damn player to do it after the fact. The result is that the videos we made with the camera held sideways are fucked.