Some issues I've found with Chrome dev tools:
* console.log() is fundamentally broken [1]. There's a bug filed for it and it doesn't seem like it will be fixed.
* When you log an HTML element, there's no way to jump to it in the "Elements" view.
* If XHR response is in JSON, it does not show you it in friendly easy-to-navigate format, but rather a big string.
Aside from that both tools are really awesome and do pretty much everything I need them to.
[1]: http://techblog.appnexus.com/2011/webkit-chrome-safari-conso...