Indeed, he didn't break the speed of sound. When he hit around an estimated 729mph, he was spinning a fair bit. It looked as if he made the decision to attempt to stabilize (I think he mentioned during descent that he thought he was going to pass out) himself at the cost of not breaking the sound barrier.

On their website they say that the speed of sound would be about 690mph at the height that he was expected to reach it, not 768mph – that speed just applies at standard temperature and pressure.

I would very much like confirmation on that point, but it seems to me that pointing to the 729mph you saw is no such confirmation.

Surely the speed of sound is much lower at that altitude, since it's so cold. Are people talking about the sea-level speed of sound?

According to the press conference, he hit 833MPH (Mach 1.24).

I don't think it has been confirmed yet, he was pretty close.

he did, just confirmed and verified by the notary.

At the moment it looks like he passed it.

On the live stream they said he topped 1173km/h. What speed was the target ? I mean speeds are defined in air and 'normal condition', there was almost no gas around him during his fall right ?

Speed of sound has a non-linear relationship with altitude.

http://www.wolframalpha.com/input/?i=speed+of+sound+at+10000...

With altitude. Non-linear with attitude would mean w/ angle of attack, which would be fascinating.

1,236 kilometres per hour (768 mph)

It was also not the "edge of space".