Sure! Here are some things I personally find exciting about FF4. I'm not saying everyone should find them exciting, they are just my personal opinion:

* FF4 is the only web browser to combine a tracing JIT with a method JIT for JavaScript. Some websites run amazingly fast with that. See the mozilla demos site for examples.

* IE9 has great hardware acceleration on Windows (but JS engine is inferior to FF4 and Chrome), while Chrome has a great JS engine (but hardware acceleration on Windows is inferior to FF4 and IE9), while FF4 is the only browser to have both great hardware acceleration on Windows + a great JS engine.

* Firefox is the only major browser that is 100% open source. (Chrome isn't open source, it bundles closed-source Flash and a PDF viewer as well as other stuff. Chromium is open source, but the vast majority of Chrome/Chromium users use Chrome.) Firefox is also developed in the open source way, completely in the open, unlike any other browser (including Chromium, where a lot of development is behind closed doors, then 'dropped' into the open - e.g., CrankShaft).

* Almost the same codebase used on desktop and mobile (mobile FF4 will hit RC very soon too). Opera has a mobile version, and Safari and IE have mobile versions too, but they are quite distinct. Firefox brings the mobile and desktop versions closer than those. Among the benefits is you can view desktop versions of websites in FF4 mobile very well. (Of course you generally want mobile versions of websites - but now and then, you do want a desktop version, especially on a tablet.)

2. Firefox Sync, which syncs bookmarks, tabs, passwords, history, and formfill data to all your different computers -- and to Firefox for Android. Firefox Sync encrypts your data client-side for privacy and security, and you can run your own sync server if you want to. (There are multiple open-source server implementations.)

See also: http://www.mozilla.com/firefox/RC/features/

Chrome 10 can encrypt everything client-side too.

http://www.google.com/support/chrome/bin/answer.py?hl=en&...

That does seem to imply that only passwords are encrypted while in storage. That's not surprising, since Chrome has a "master password" for password encryption, but unlike Firefox it does not require transferring an encryption key for your other sync data. (The client-side encryption key is the reason you need to "pair" your devices to set up Firefox Sync, instead of just entering a username and password.)

https://demos.mozilla.org/en-US/

There doesn't have to be only one browser, right? We want a few great implementations of the open standards.

Extensions. Firefox has the greatest browser extension ecosystem bar-none. In the past, you had to choose between Chrome's performance, and Firefox 3's extensions.

Certainly Firefox was playing catch-up in performance, but we're there now. Chrome is still far far behind in terms of extensions, and showing no sign of catching up.

Simply put, Chrome extensions are HTML/CSS/JS, while Firefox extensions can actually manipulate the interface of the browser to a greater degree (making stuff like Vimperator possible when it wouldn't be possible on Chrome)

On Ubuntu in particular (but on other Linux distros, too), Firefox 4 has a more platform-appropriate appearance and feel than the other cross-platform major browsers (Chrome and Opera).

For Web authors, there are more polished HTML5 form features to get excited about. For HTML5 feature involves new elements or attributes in markup, the chances of the features present in Firefox being polished is higher than the chances of the features present in Chrome being polished even though it might casually appear from html5test.com that Chrome support a larger number of these features. html5test.com tests if new APIs appear to be present--not if all the default user interaction works right or if the appearance of a feature is pretty across platforms (not just Mac and Windows but Linux, too).

The location bar history search in Firefox is remarkably more useful than in Chrome, because Firefox matches on more things than just the prefix of the URL (though Chrome has better search coming up and already available in about:flags).

Well, actually, syncing browsing history and passwords across browser instances in such a way that the data in encrypted and decrypted on your devices only is well worth repeating although it was mentioned already. (Syncing history and passwords is immensely more useful than just syncing bookmarks or sending over individual URLs, but history and passwords are the most sensitive browser data, so end-to-end crypto between the user's devices is important.)

(Disclosure: I'm consulting for Mozilla. Disclaimer: Speaking only for myself, though.)

In addition to all kinds of new HTML5 support, there's hardware acceleration, awesome SVG support, robust Audio API, and Panorama (press cmd+shift+e).

I'd go a step further and say that now there are going to be an increasing number of Chrome users who will compare to Firefox 4 and want the performance and feature improvements that it has over Chrome and that may hold true for some time.

So, yes, you could look at it that way.

http://mikewest.org/2010/12/intro-to-indexeddb

* Password manager with a master password.

* Different Awesome Bar behaviour (which some prefer to Chrome's)

* Delicious extension (the Firefox one blows away the Chrome one)... although that doesn't seem to work in 4.0 yet.

Until Chrome catches up to Firefox in features, I'm excited about a release of Firefox which catches up to Chrome in speed.

Chromium will use your native password manager if possible. For example on KDE it will use KWallet to store passwords.

Another thing, Firefox4 allows you synthesize audio in Javascript, something that Chrome (AFAIK) can't do yet.

https://wiki.mozilla.org/Audio_Data_API

You are right, if you are not hooked on some extensions chrome is a good option, my wife is a full time chrome user.

https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta...

One other thing. It's small, and non technical, but I find I really like the very compact implementation of the pin tab feature. The way FF adds subtle indicators when the content on a pinned page updates is especially nice.

I'm on Chrome 10.0.648.127 and it does a periodic glow when pinned content has been updated. It's a little too subtle for my tastes, really.

basically because of adblock plus and firebug i did newer jump on chrome bandwagon and i really like the firebox 4.