Opera is similar and based on Mozilla. Having changed to it over the past two weeks, I have really grown to like it.
The main advantages as far as I am concerned, is the ability to customize it's presentation, and the ability to block pop-ups, which to me, are a constant source of annoyance. If your into differnt skins or colours, there are a wealth of addon's avilable. Multi-pages are available within the same Window, so the overhead of running multi-screens is greatly reduced. These are selected in tab format, similar to the tabs on a spreadsheet for example.
It will run happily side by side with IE, so you can install it, try it, and if it's not your taste, uninstall it, without upsetting your IE installation.