|Battleship grey, and a bit uninspiring|
I was part of the beta test group that used Firefox 4, and I used it on both my PC and my Mac. The deeper into the beta testing, the worse it got. Consider the initial look - it's really, really ugly. The tabs are uninspiring compared to Chrome, and the battleship grey on the Mac makes me throw up a little in my mouth. Googling for "Firefox fonts look bad" turns up a whole host of people who noticed too. It looks pretty bad, and the solution appears to be messing around with settings in the about:config.
Another oddity is that the download size has also more than tripled. The last version of the 3.x series was just over 8MB. The 4.x series comes in at a whopping 28MB. Not huge by today's standards, but certainly noteworthy in it's stark contrast from the previous trim-and-slim size. Firefox 4 has put on some sizable love handles, without much to show for it.
The one new feature that appears to be somewhat innovative is the "tab groups". This is sort of a task manager for your browser windows. It seems neat at first, but it winds up being a solution in search of a problem. Other than an initial time playing around, I've never felt the need to use this feature. I find that when I get too many tabs, I just open a new browser window. Then, you can actually drag tabs from one browser session to another. Problem solved without this "tab groups" thing. It seems like a lot of wasted development, which may have been part of why the download is so big and the final release was delayed so long. Tab groups would have been better suited to a plug-in than a bloated browser feature.
What's most notable to me about Firefox 4 isn't so much what's in it, but what's missing. The orange RSS feed button that showed in your URL bar when a site you visited had a feed is sadly gone. It's replaced with a hidden toolbar button, much like the bookmarks button that you have to find in the toolbar customization dialog. However, it's really difficult to tell when the button is lit up indicating an available feed, so it's just not nearly as nice as the original. Mozilla got this feature right a long time ago before any of the other browsers did, and then they threw it all away.
The other head-scratcher is that they ditched the status bar, which is the bar that sits at the bottom of your screen and tells you what site you're about to go to when you hover over a link. This move was presumably to mimic Chrome and regain some screen real estate for page content. The trouble is, Mozilla also had this one right too and blew it. Chrome lets its plugins take up precious space in the primary menu bar, whereas many Firefox plugins like Grease Monkey and Add Block Plus sit out of the way on the status bar. So great is the love of the status bar, that there is a plugin called Status-4-Evar that brings it back which has over 100,000 downloads already.
As far as quick, stable and functional, Firefox 4 does well here. But frankly, that's to be expected from a browser that isn't Internet Explorer. But much the same way the only thing John Kerry had going for him was that he wasn't George W. Bush, I'm not sure that just being better than Internet Explorer is going to work out for Firefox in the long run. And I'm not convinced they're that much better than IE anymore... with IE9 now clearly the best browser ever to come from Microsoft, as well as Chrome being the best browser available today, Firefox is going to have to step up its game. They need to quit pulling features that work and people love, quit trying to be Chrome and doing it badly, and quit coming up with complicated solutions to simple problems in an effort to look innovative.