Why should switch? Speed and less memory is a major factor. You can read about the technology. Or you can just believe it must be something different and big when the giant company like Google and Microsoft joint together. Just belive it, just a matter of time.
The obvious different is the tabs use different exe file so if we close a tab, the space will be complete empty.
They also has created buletin board community encourage people build and share the plugins or themes for Chrome.
For now I still use Firefox evetime I need firebug, web developer plugins and measure it. But this is just the beginning – Google Chrome is far from done. A seed of a huge tree has been seeded, I just believe.