I have been trying out the Opera 10.6 beta for Linux and I have got to say im very impressed. The main difference is the developer tools which if you are used to firebug you will feel very at home with. The tools are called Dragonfly and instead of taking a different direction like Safari and web-kit, they have stuck closely to the firebug system but made it natively part of the browser.

For windows users the Browser is full released but the Linux and OS X version are in beta. Well worth giving a go!