1 Why is Chrome spawning a new browser engine?
The WebKit maintainers wouldn’t let us attack Apple directly, by changing WebKit in ways that would make it perform badly on OS X and iOS.
Because they share a rendering engine, developer effort to ensure Chrome compatibility currently benefits Apple platforms for free. To prevent this, we must make Chrome and WebKit behave differently.
1.1 What sorts of things should I expect from Chrome?
Nothing yet. This is a political move, not a technical one.
However, while the Chrome user interface will not change in any significant way, we will be silently overwriting all existing installations of Chrome with our new rendering engine without your knowledge or consent.
…continues gloriously at Chrome Blink FAQ.