Well, SIM working now
Nice little handset. Sound is surprisingly punchy for the type of handset. Radio is decent with headphones plugged in for aerial.
Screen is decent for a basic phone and responds OK to touch. Accuracy may be a little low but I am never exceptional with this anyway!
Other installed apps are music and video players, alarm, calculator, mail, notes, maps etc.
Got the mail running OK and again seems slick enough. Not as advanced as Android. attachments have to be added from the area they exist - i.e email pics from album, rather than attach to message.
Much of the phone is based on web as expected. Firefox browser does the main job and seems good a rendering pages etc. Pinch and zoom is OK, maybe not ultra responsive. There is an 'app' store which so far has a few big hitters and quite a few other lesser known apps. Not tried any yet though.
Then there is also what I would describe as web apps. Rather than installed, you search for various subjects, weather, tv, etc and it brings back apps related to specific websites, for example Met Office or Sky. More refined searches bring customised pages - weather and Wales shows Google app for that area.
I think this is what they have been pushing as html5 developing where anyone should be able to do an app if they know web stuff.
I'll comment more as I use it or other questions specifically.
One other point, I also have the basic Lumia 620. On the face of it this is a much more polished affair and does feel a premium cheap phone - if there can be such a thing! Having said that, the Firefox device is half the cost so take it in perspective.
It will be interesting to see how it develops and especially if it can get pushed just that little further hardware wise, but I think keeping it simple and low cost may help.