http://www.mozilla.org/en-US/firefox/partners/This page is a good read --- things to remember are:
Firefox can run well on a single core processor and that Firefox does not require a lot of memory either, 512k is more than enough. This is very important for the very large populations in third world countries that are just now getting their first phones.
Firefox phones can cost less than $100 to buy outright -- for a 2 year plan they would be free "feature phones" to Verizon or AT&T.
Firefox has avoided legacy issues with Flash and Java -- from the get go these issues are gone.
Firefox is HTML 5 based and it intends to run HTML 5 apps either directly loaded from the Firefox Store or it can reach out and touch them through the net (allows the server farm's processors to do all the heavy lifting).
On a dual or quad core processor, Firefox screams speedwise.
By staking out the future, Firefox will possibly own it when it the future matures. By being the first phone that the 6-8 BILLION new phone and tablet owners ever get, Firefox will be what they recognise as an OS from the very beginning.
Firefox on a TV screen through a pre-existing stick PC will complete the third world convergence troika, allowing the new third world computer user folks to have convergence from the beginning on all of their devices. This is a very big, as it will be the "convergence support" that all OSs will be required to have before long.
Remember Ubuntu Edge? A current spec'ed quad cored relatively good phone could do this trick with Firefox OS right now.
Android has gotten somewhat hardware intensive lately and Google has ticked the Far Eastern phone suppliers off by not letting them screw with the last 2 Android flavors for very much. Indeed, Google has restricted Play Store access in an attempt to get everyone to standardize on a Google standard interface (which I like, BTW). This doesn't mean the far eastern phone suppliers like it though.
=================
Things that are not so good with Firefox is that it is still being polished as far as an interface look/feel goes. It looks about like an unpolished Android from 2 years ago .... Also, look out for too much customization becoming somewhat of a barrier to progress (it happened with early Android, so history may repeat itself with Firefox OS).
So .... give it a year to grow up some, then consider the Flash and Java content (that here in the USA) you are still going to want. Netflix and YouTube are real considerations to cover before going to a Firefox phone or tablet.
Firefox as a browser always seems to grow add-ins to do whatever the heck people want, and I think that any lacks in the base Firefox phone/tablet OS in any given marketplace could be addressed that exact same way.
====================
Google, your move now.
You have been dicking around
avoiding releasing a full convergent OS for a while now. We know you have one already finished and sitting on the shelf ..... waiting .....
Waiting for what? For Rockchip or Ubuntu or Cyanogen Mod to do it before you?
You currently own Tablet and Phone space and Microsoft is on the ropes and Apple has totally lost it's mojo. You have been resting on your laurels for the last year, taking it easy. Time to pick up the pace, boys.
PAY ATTENTION ..... Firefox is going to take a big chunk out of your worldwide market share next year (and about all of Microsoft's and some of Apple's) unless you get PRO-ACTIVE and release some of the wonders you have been lazily working on in them back rooms for the last 2 years ......
If you screw up and do an Apple/Microsoft and go into hardware manufacturing, then you will lose what you have built up to this point. If you do nothing, you lose as well.
Cooperating and helping the Ubuntu's and Firefox's as needed and being a true open source company is your best bet. Read and do your own core mantra ..... "Do no evil".
Help Cyanogen Mod/Ubuntu folks finish their efforts or else you go ahead and release your own convergence OS package for the US market.