It took just 30 seconds to make up my mind. Google’s new map, driving direction, yellow page site is good! I have used Yahoo Maps for years but neither it nor Mapquest hold a candle to this. Julie puts it succinctly:
DHTML-driven (IE/Firefox only right now, I believe, but YMMV) maps service. Driving directions, yellow pages, etc. Drag-the-map with your mouse, DHTML controls, no more of that click-wait, click-wait, click-wait, click-wait never-quite-right map manipulation.
Try it out. Change now!
Update: Barry provides some usage tips and suggests that this might be a good front end for Keyhole, another Google product.
Update II (2/9): Via Zomboyboy here is a more technical look at this tool.