You can push it pretty far. I'm really impressed with the quality of the video. They definitely need a lot of light though and they suffer a bit when you go through changing conditions (sun/shade/sun). If they can ever get a CCD sensor to fit into that case, instead of the CMOS, all I can say is, holy crap.
Here's a great site for accessories. Lots of handy stuff there such as a polarizer filter and mag mount. I know the guy that runs it from my surf photography days.
Most fun I've had with it though is with the girls skiing. Been great to capture their first intro to skiing with it.
(sorry, embed wasn't showing up for some reason...)