Few months later my opinion is still the same. I eagerly await the new beta version, and I tend to watch closely the
http://arewefastyet.com, which appears to have some good progress. Mostly, I use Firefox because of habits - I certainly don't want to break them, and useful addons that make my web life much easier. I also found kinda difficult to integrate another browser in my Linux workstation, which is also tied to using Thunderbird as mail and RSS client. Mozilla, however, really need to address the speed issues - both in JS engine and UI being clumsy sometimes. Fortunately, their plans include exactly these, plus some other useful features.