Editors' note: Portions of this review are based on CNET's review for Firefox 4 for desktops.
Mozilla's first foray into the Android Market ports much of the desktop Firefox experience to your mobile device. The look and feel of the desktop browser have been remarkably replicated, and the browser itself doesn't feel alien compared with other Android browsers.
If you have a Maemo phone, you can download Firefox 4 Mobile for Maemo devices. Except for the performance benchmarks detailed below, it's safe to presume that the Android and Maemo behaviors are close enough to use this review as a guide to the Maemo version.
Firefox 4 beta 4 for Android
Installing Firefox 4 Mobile is no different than any other Android app, except that the installer is significantly larger than most Android apps. The basic Firefox installer takes up about 13MB on your phone, so be sure that you have enough room to store it. Alternatively, you can transfer it to your SD card before running it for the first time.
Once running, Firefox for Android will require about 17MB total. The extra 4MB comes from browsing and synchronization data. Firefox's APK is so large, especially when compared with the default Android browser, which takes up less than 1MB of space, because Firefox includes its own rendering engine. Most other third-party browsers on Android still use the default browsers' WebKit engine.
Note that Firefox for Android works best on more-recent devices. Two notable phones that it does not work on are the first Motorola Droid and the Droid Eris. Mozilla says that they're basically too underpowered to support the browser. The company has a list of supported devices and other requirements.
Firefox 4 Mobile's interface starts you off differently than its desktop counterpart, with a new Firefox Start page. It's a landing page that provides buttons to several key browser functions. You can reload your tabs from your previous session, peruse and load tabs from other computers, and tweak add-ons. For example, if you install the Personas add-on for skinning the browser, a button will appear on Firefox Start to quickly get you to the Personas management page.
Above Firefox Start lives the location bar. Favicons are larger in Firefox than in the default browser, which makes it easier to check at a glance which site you're on. Tap the favicon to see site security information, as well as tools to save the page as a PDF, search within the page, tweak character encoding, and see relevant add-ons. AdBlock Plus will appear here, for example.
As in the desktop version, you can search directly from the URL bar. Tap it and you'll jump to a window with four tabs that Mozilla calls the Awesome Screen. The first tab is All Pages, which shows all the sites you've visited. The next tab is Bookmarks, and if you've enabled Sync, your desktop bookmarks will appear in a separate folder here. The third tab is your History, and the fourth is Desktop for showing tabs from your Firefox desktop--again, this is dependent on using Firefox Sync.
Drag the site you're on to the right to see tab management, with each tab represented by a thumbnail. Dragging your finger across the screen to the left shows you the star for quickly bookmarking a site, forward and backward navigation buttons, and an Options button for accessing Firefox's Preferences, Add-ons, and Downloads window.
Hitting the hardware Settings button gives you four more options via tabs: Site options, which is the same as tapping a site's favicon; and Preferences, for customizing Firefox. The next two choices are add-ons for managing your extensions, followed by a downloads manager.
The interface design is intuitive and ought to present a very gentle learning curve. It's probably helpful for new Android users to remember that for bookmark and history-related searches, tap the location bar at the top of the browser. For tweaks to Firefox itself, tap the hardware settings button and your options will appear at the bottom. Most importantly, transitions between screens in Firefox 4 Mobile were smooth and suffered no lags.
Features and support
Firefox 4 Mobile's features are robust and competitive, bringing user favorites like Firefox's add-on community to Android along with important usability features like the aforementioned Firefox Sync, clever search engine switching, and blazing browsing times with its own rendering engine.
How to sync Firefox 4 to Android
The most important new feature in Firefox 4 Mobile is Firefox Sync. As with many recent Firefox features, it started off as a rough add-on for the desktop, and often deleted data. If you were scared off by its early bad behavior, you'll be glad to know that Mozilla has worked out the kinks: Sync now smoothly syncs your Bookmarks, Passwords, Preferences, History, and Tabs to both multiple desktops and multiple Android devices.
Unfortunately, Firefox Sync does not support syncing add-ons, even when there are versions for both desktop and Android such as AdBlock Plus. Hopefully this will come in future versions, or at least Sync will be improved to include an advanced users' panel for those who want more customization in their synchronizations.
That all being said, Firefox Sync is a powerful feature that works well, and it keeps your desktop data cleanly separated from your mobile browsing in folders and options labeled "desktop," yet that separation doesn't impair your ability to access them. This is a top-notch synchronization implementation.
To use it, go to Preferences and make sure that Enable Sync is checked off. Then tap the Connect button, and enter in the code that appears in your desktop version of Firefox. If you're not near your desktop, tap the link that reads, "I'm not near my computer" and follow those instructions.
Within Firefox Sync, there are two important security points. One is that Firefox encrypts your data before sending it over an encrypted connection to its servers, where it remains encrypted. Mozilla says that the company would not be able to access it even if somebody there wanted to. The second is that you have the option of setting up your own personal sync server. In an age when private data stored by corporations gets hacked and stolen with shocking regularity, setting up a personal sync server is one way to ensure that you bear the responsibility for your own data.
Another big feature in Firefox 4 Mobile is support for add-ons. There's a small collection of these so far, only around 150 at the time this review was written. Of those, however, there are many which are among the most popular of Firefox's desktop add-ons including AdBlock Plus, NoScript, Personas, and Readability. There are numerous search engine add-ons, which makes it easier to search specific sites from your device. These include IMDB, Twitter, YouTube, and Bing.
A cool search engine feature that Mozilla has built into Firefox mobile is that when you start typing in the location bar, Firefox will offer your search engines with the term you just typed in as automatic results. So, if you type "cheese," along with your previously visited "cheese.com," you'll get "Google--search for cheese" as a one-tap alternative. Another cool search tweak is that because of the Awesome Screen's All Pages default tab, which functions as a dumping ground for all URLs you have visited and have bookmarked, it can search your history quickly. That, too, will cut down on typing and tapping. These are key time-saving features on a mobile device, especially those with smaller screens.
However, Firefox 4 Mobile does not support Flash, even when you've installed the separate Flash app from Adobe. It's not clear at the time of writing whether Mozilla plans to include support in a future update, either. This sets it behind many of its competitors which do support Flash, including the default browser, Opera Mobile, and DolphinHD.
There's no doubt that Firefox mobile renders Web sites faster than the default browser. It also feels more cohesive, as the discrete elements of pages appear quicker.
Much of this has to do with the new JaegerMonkey engine getting ported to the mobile version. We'll update this section with CNET's performance benchmarks as they become available, although initial results show Firefox 4 testing competitively against other browsers.
Initially, we thought that Firefox for Android suffered from some serious lag when starting up. It turns out that this was related to upgrading from the beta test version to the one that's currently available to the public. If you're experiencing slowness when starting the browser and you were a Firefox beta tester, it's worth your while to uninstall it and then download it again.
Definitely a worthy heir to the Firefox name, Firefox 4 Mobile is likely to become many desktop Firefox users' default browser simply by virtue of Firefox Sync. The feature is simply impressively useful, and will become even more so if users begin adopting Android tablets like they've taken to Android phones.
However, the lack of Flash support is a definite problem, as is the horrifically slow lag when loading the browser. It's enough to keep the browser from getting top marks, as much as we really like just about everything else about using Firefox on an Android.