This is a web developer & user review of Firefox OS 1.1 on the Geeksphone Keon. Warning: this is a developer preview of an entry level smartphone (around 92€ + vat).

There are already some stories about the Firefox OS platform, so I'll concentrate on the differencies

Firefox OS

It's a complete Web oriented mobile Operative System. It means you can reuse you web technologies knowledge (HTML5 + CSS + JS) to adapt your websites/webapps or build offline applications with the same technologies. FirefoxOS : smartphones = ChromeOS : netbook|ultrabook

Behind the scene FxOS reuse the kernel Linux and some other parts of Android but not the Java VM layer (see architecture and the SDK WebAPI).

So why should you get excited?

It already works well on low spec devices

Write / Buy one, run anywhere

It already supports Webgl (on some high specs ureleased smartphones)

How to develop on Firefox OS

You can submit your webapp to the Firefox Marketplace without much effort, you just need to add a file to your website named manifest.webapp with some fields filled. There is also a Firefox OS Simulator which is very fast compared to the Android one.

What is missing in Firefox OS 1.1

I know it's a young platform, but Firefox OS is already released in Latin America, Poland and other countries, so here is my personal list:

Cut and paste

an accurate AGPS service. Now it works, but the first days I was geolocalized 500km far from where I am.

"find" in Firefox browser!

the switch to use it in GSM only mode (some operators charge for 2G or 3G connections if you dont have a data plan)

Better debugging tools.. it seems when you "install" an online webapp some parts are cached and it works differently than in the browser. I noticed in my app Geospot with notifications.

The possibilty to download stuff, there's an ePub and a Pdf reader but I wasn't able to use them offiline

AdSense doesn't work on Firefox Mobile. This mean less casual Flash-like games in HTML5 tested on FxOS

The Facebook and the Twitter web app doesn't implement the notifications and Soundcloud doesn't play in background

Flashing other ROMs

The OTA update from Geekphone was alwais corrupt so I flashed latest stable manually (you need a 32bit cpu or the Android tools installed). Latest v1.1 rom works very good on the Keon, while the 1.2 series has video recording broken and frequent wifi disconnection.

Conclusion

The duopoly Android / iOS is strong but Firefox OS has really some interesting points over the competitors: it's already interesting compared to low-spec Android smartphones and it doesn't reinvent the wheel: many website are already responsive, why should you make a native app for iOS, Android, Windows Phone, Tizen, Jolla, Blackberry, Ubuntu Phone .. just to have native push notifications? You can already do it in Fxos without objective-c or java. OpenWeb is the current Web without lock-in an the future.