I've been excited about, and have used Firefox as a secondary or, when it hit version 1.0, primary browser when it was called Firebird. It's been a great, secure and fast browser that works with the latest CSS and DHTML. Over the years, it's gained many useful features and extensions such as Web Developer and Sage (for RSS)... both of which I used(ed) very often. Features like these made it so that I can take my browser, and add in only the features I want.
I'm a bit disappointed that Apple has kinda forced this on me... I mean, their new OS is what slowed Firefox down. But until some things can be fixed at Mozilla, the Apple way, for me at least, is the best way.