I've just tried to read and reply to some posts on here on my mobile, and it's a complete disaster, totally unusable.
Although some form of responsive design comes through, the design is broken, so that the text in posts takes up about 150% of the screen width, regardless of orientation, and I can't zoom out to get more on, I have to keep panning left and right on every line. No thank you, that is not a functioning system.
Lots of the icons don't work either, which I think is because they are not icons but glyphs from an embedded font. Unfortunately, Windows Phone doesn't support embedded fonts, so all I get are little boxes to show where there should have been an icon, but no indication whatsoever of what it should be.
The reply box doesn't work properly either, and the first few lines of text are obscured by a series of empty boxes that should show the glyphs representing formatting buttons on the reply box, but not only are these unintelligible but they cover up the text of my reply, so I can't even see what I'm typing.